The US has announced plans to send forces to Saudi Arabia in the wake of attacks against the country's oil infrastructure.Secretary of Defense Mark Esper told reporters the deployment would be "defensive in nature". Total troop numbers have not yet been decided.Yemen's Iran-backed Houthi rebels have claimed responsibility for the attacks against two oil facilities last week.But the US and Saudi Arabia have both blamed Iran itself.What are Trump's options on Iran?Earlier on Friday however, President Trump announced "highest level" sanctions against Iran while signalling he wanted to avoid military conflict."I think the strong person approach, and the thing that does show strength, would be showing a little bit of restraint," he told reporters in the Oval Office.The fresh sanctions will focus on Iran's central bank and its sovereign wealth fund, Mr Trump said.What did the Pentagon say? Mr Esper made the announcement alongside the chairman of the Joint Chiefs of Staff, Gen Joseph Dunford Jr on Friday. Saudi Arabia and the United Arab Emirates requested assistance, Mr Esper said. The forces will focus on boosting air and missile defences, and the US will "accelerate the delivery of military equipment" to both nations.
Secretary of Defense Mark Esper, left, and Chairman of Joint Chiefs of Staff General Joseph Dunford made the announcement on Friday
Gen Dunford called the deployment "moderate" and said it would not number in the thousands. He gave no further details about the type of forces to be sent.According to the New York Times, when reporters asked Mr Esper if military strikes on Iran were still being considered, the defence secretary responded: "That's not where we are right now."
What happened in Saudi Arabia?Strikes hit the Abqaiq oil facility and the Khurais oil field in Saudi Arabia a week ago, affecting the global oil supply.On Wednesday, the kingdom's defence ministry showed off what it says are the remains of drones and cruises missiles proving Iranian involvement. The country is however still "working to know exactly the launch point", a spokesman said.
The US also alleges Iran is responsible. Senior officials have told US media outlets they had evidence the attacks originated in the south of Iran.Iran has repeatedly denied any role in the strikes, with President Hassan Rouhani calling the attacks a reciprocal act by the "Yemeni people"."US is in denial if it thinks that Yemeni victims of 4.5 yrs of the worst war crimes wouldn't do all to strike back," Iran's Foreign Minister Mohammad Javad Zarif tweeted.Who's using armed drones in the Middle East?Why Saudi Arabia and Iran are bitter rivals On Wednesday, Secretary of State Mike Pompeo had called the strikes "an act of war".Mr Zarif warned on Twitter that Iran had no desire for war but "we will not hesitate to defend ourselves".
What's the background to all this?The Houthis have repeatedly launched rockets, missiles and drones at populated areas in Saudi Arabia. They are in conflict with a Saudi-led coalition which backs a president who the rebels had forced to flee when the Yemeni conflict escalated in March 2015.Iran is the regional rival of Saudi Arabia and an opponent of the US, which pulled out of a treaty aimed at limiting Tehran's nuclear programme after Mr Trump took power.US-Iran tensions have risen markedly this year.The US said Iran was behind attacks on two oil tankers in the Gulf in June and July, as well as on another four in May. Tehran rejected the accusations in both cases.
Why Saudi Arabia and Iran are bitter rivals
Saudi Arabia and Iran are at loggerheads. They have long been rivals, but it's all recently got a lot more tense. Here's why.Saudi Arabia and Iran - two powerful neighbours - are locked in a fierce struggle for regional dominance.The decades-old feud between them is exacerbated by religious differences. They each follow one of the two main branches of Islam - Iran is largely Shia Muslim, while Saudi Arabia sees itself as the leading Sunni Muslim wer.This religious schism is reflected in the wider map of the Middle East, where other countries have Shia or Sunni majorities, some of whom look towards Iran or Saudi Arabia for support or guidance.Historically Saudi Arabia, a monarchy and home to the birthplace of Islam, saw itself as the leader of the Muslim world. However this was challenged in 1979 by the Islamic revolution in Iran which created a new type of state in the region - a kind of revolutionary theocracy - that had an explicit goal of exporting this model beyond its own borders.In the past 15 years in particular, the differences between Saudi Arabia and Iran have been sharpened by a series of events.The 2003 US-led invasion of Iraq overthrew Saddam Hussein, a Sunni Arab who had been a major Iranian adversary. This removed a crucial military counter-weight to Iran. It opened the way for a Shia-dominated government in Baghdad and Iranian influence in the country has been rising ever since.
Fast-forward to 2011 and uprisings across the Arab world caused political instability throughout the region. Iran and Saudi Arabia exploited these upheavals to expand their influence, notably in Syria, Bahrain and Yemen, further heightening mutual suspicions.Iran's critics say it is intent on establishing itself or its proxies across the region, and achieving control of a land corridor stretching from Iran to the Mediterranean.How have things got worse?The strategic rivalry is heating up because Iran is in many ways winning the regional struggle.In Syria, Iranian (and Russian) support for President Bashar al-Assad has enabled his forces to largely rout rebel group groups backed by Saudi Arabia.Saudi Arabia is trying desperately to contain rising Iranian influence while the militaristic adventurism of the kingdom's young and impulsive Crown Prince Mohammed bin Salman - the country's de facto ruler - is exacerbating regional tensions.
Five things about Saudi Arabia's Crown Prince Mohammed bin SalmanHe is waging a war against the rebel Houthi movement in neighbouring Yemen, in part to stem perceived Iranian influence there, but after four years this is proving a costly gamble.Iran has denied accusations that it is smuggling weaponry to the Houthis, though successive reports from a panel of UN experts have demonstrated significant assistance for the Houthis from Tehran in terms of both technology and weaponry.Meanwhile in Lebanon, Iran's ally, Shia militia group Hezbollah, leads a politically powerful bloc and controls a huge, heavily armed fighting force. Many observers believe the Saudis forced Lebanese Prime Minister Saad Hariri, whom it backs, to resign in 2017 over Hezbollah's involvement in regional conflicts. He later returned to Lebanon and put the resignation on hold.
There are also external forces at play. Saudi Arabia has been emboldened by support from the Trump administration while Israel, which sees Iran as a mortal threat, is in a sense "backing" the Saudi effort to contain Iran.The Jewish state is fearful of the encroachment of pro-Iranian fighters in Syria ever closer to its border.Israel and Saudi Arabia were the two countries most resolutely opposed to the 2015 international agreement limiting Iran's nuclear programme, insisting that it did not go far enough to roll back any chance of Iran obtaining the bomb.
Who are their regional allies? Broadly speaking the strategic map of the Middle East reflects the Shia-Sunni divide. In the pro-Saudi camp are the other major Sunni actors in the Gulf - the UAE and Bahrain - as well as Egypt and Jordan.In the Iranian camp is Syria's President Bashar al-Assad, a member of a heterodox Shia sect, who has relied on pro-Iranian Shia militia groups, including the Lebanon-based Hezbollah, to fight predominantly Sunni rebel groups.
Iran and Saudi Arabia: Their friends and foesIraq's Shia-dominated government is also a close ally of Iran, though paradoxically it also retains a close relationship with Washington on whom it has depended for help in the struggle against so-called Islamic State.How is the Saudi-Iranian rivalry being played out?This is in many ways a regional equivalent of the Cold War, which pitted the US against the Soviet Union in a tense military standoff for many years.Iran and Saudi Arabia are not directly fighting but they are engaged in a variety of proxy wars (conflicts where they support rival sides and militias) around the region.Yemen is one of a number of battlegrounds fuelling Iranian-Saudi tensions
Syria is an obvious example, while in Yemen Saudi Arabia has accused Iran of supplying ballistic missiles fired at Saudi territory by the rebel Houthi movement.Iran is also accused of flexing its muscle in the strategic waterways of the Gulf, through which oil is shipped from Saudi Arabia. The US says Iran was behind recent attacks on foreign tankers there - something it denies.
Are we heading towards a direct war between Saudi Arabia and Iran?So far Tehran and Riyadh have fought via proxies. Neither is really geared up for a direct war with the other but a major Houthi attack against the Saudi capital or, as in the most recent case, against a key economic target could upset the apple cart.US says data shows Iran behind Saudi oil attacksThe huge US oil stash hidden in underground cavesHouthi attacks against Saudi Arabia's infrastructure have inevitably added a new front to the confrontation between Tehran and Riyadh. As in the Gulf, where Iran and Saudi face each other across a maritime border, rising tensions could risk a much broader conflict.
For the US and other Western powers, freedom of navigation in the Gulf is essential and any conflict that sought to block the waterway - vital for international shipping and oil transportation - could easily draw in US naval and air forces.For a long time the US and its allies have seen Iran as a destabilising force in the Middle East. The Saudi leadership increasingly sees Iran as an existential threat and the crown prince seems willing to take whatever action he sees necessary, wherever he deems it necessary, to confront Tehran's rising influence.Saudi Arabia's vulnerability has been demonstrated by these latest attacks on its oil installations. If a war breaks out, it will be more perhaps by accident rather than design. But the Saudis' own activism, encouraged in part by a lingering uncertainty as to the Trump administration's own goals in the region, inevitably adds another element of tension.
Saudi Arabia oil attacks: Trump blames Iran but what are his options?
Jonathan Marcus
Diplomatic correspondent
Saudi Arabia says Iran was behind the attacks on its oil infrastructure As he struggles to define a response to the attacks against key elements of Saudi Arabia's oil infrastructure, President Donald Trump has insisted that he has many options.He has already chosen to employ one of them, ordering stepped up economic sanctions against Tehran - which denies carrying out the attack - and doubling down on the policy of "maximum pressure" against Iran which the US insists is having a significant impact.The problem is that many critics of the administration believe that it is this very policy, President Trump's decision to abandon the international nuclear agreement with Iran and step up economic pressure, that has brought us to this current point. So what can the Americans do? What really are the options? Is this really America's business? And if so, what is the likelihood of some kind of military response to an attack which the Americans clearly believe came from Iran?First it is important to realise that any action can be immediate or it can play out over time. It can be overt, in the full glare of publicity, or it can be covert, hidden from public view. First though, the US and the Saudis need to make the public case; to establish clearly what happened and to provide corroborating evidence that places responsibility firmly with Tehran. This will provide the public and legal case for any response and it will help to garner wider international support for any steps taken.
Attack on Saudis destabilises already volatile region This was, after all, according to US Secretary of State Mike Pompeo, "an act of war". Despite all the Iranian denials the information released so far shows Iran to be deeply implicated in these attacks. But much more detail is needed, not least an answer to the crucial question: was this attack, as some US officials say, actually launched from Iranian soil? Once the case has been made, what then can President Trump do?
Economic pressureWhile there are no details as yet, the president's initial response has been to call for more economic sanctions. There is no doubt that the Iranian economy is hurting. That, many analysts say, is why Iran may have decided to strike at Saudi Arabia's oil infrastructure now. It is a warning that Washington's economic war against Tehran can be met by an Iranian response against Riyadh. The attacks have demonstrated Saudi Arabia's extraordinary vulnerability, a factor that has to be central when considering any military riposte.
Saudi's Abqaiq oil facility was struck in the early hours of Saturday morningThe other problem with simply stepping up the "maximum pressure" campaign is that there is not much left for the US to do. The economic pressure gauge is pretty much already at maximum. Over time the impact of this campaign on Iran will get worse. But despite US claims that it is working, few analysts see any sign of Iran moderating its wider behaviour in the region. If anything, pressure is building and Iran's allies and proxies like Hezbollah or pro-Iranian militias in Iraq are only getting stronger.
A military responseThere was a time when an attack against oil supplies in the Gulf would have been a clear red line for the Americans, prompting a massive and predictable show of force. Oil fundamentally is what gives this region its strategic importance.But things are changing. The US now gets a growing proportion of its oil from its own supplies. It is hard to say if President Trump, for all his rhetoric and flattery of the Saudi royals, really sees these recent attacks as compromising a profound US national interest. He is clearly a president who wants to end US military adventures abroad and not start new ones. And for a variety of reasons, Saudi Arabia is losing more friends than it is winning on Capitol Hill.
But suppose the US decides that its vital interests are at stake, what then? The military options and potential target lists vary. The real question is: what is the use of force intended to achieve? It could for example be a token strike - like the attack Mr Trump ordered against a Syrian chemical weapons base, which did little to deter the Assad regime and its further use of chemical weapons drew no additional US response.
US Secretary of State Mike Pompeo held talks with Saudi Crown Prince Mohammed bin Salman on WednesdayAlternatively if a real military effect is intended, then any strike would have to be carefully calibrated - proportional in the sense that it matched the scale of the severity of the attack against Saudi Arabia, but also strong enough to send a clear message of deterrence.The risk of escalationOne man's deterrence though is another man's provocation. Iran shows no signs of being cowed. And there is a real risk that tensions between Iran and the US could descend into outright conflict. So where might such a conflict go and what would it look like?There are many variables to consider and it is easier to say what will not happen. The Trump administration may be an implacable foe of the Iranian regime but there is not going to be a full-scale ground invasion of Iran to topple it. This is not Saddam Hussein's Iraq. Iran is an altogether more complex challenge, both militarily and politically. Some in the White House clearly want regime change. They are likely to be disappointed. So rule out a major land war.The US can deliver punishing strikes against Iran's military infrastructure. But Iran has the means to strike back too. It can use a variety of measures from mines, swarming small boat attacks or submarines to disrupt operations in the confined waters of the Gulf. Oil tankers could be attacked, forcing the Americans to take steps to protect them too.
Iraqi PM Adel Abdul Mahdi says diplomacy can still avert warWhere the US clearly has an extraordinary advantage is in intelligence-gathering and situational awareness. But as the downing of a highly sophisticated American drone in June shows, there are significant US vulnerabilities too. Operating modern warships in the confined waters of the Gulf presents a variety of challenges. All Iran may think it needs to do is to damage or sink a few US vessels to make the price of this conflict one that Mr Trump will not want to pay.Iran, if under sufficient pressure, might also seek to spread the conflict more broadly, urging its proxies in Iraq, Syria or elsewhere to attack US targets. In extremis it might even try to prevail upon Hezbollah (in concert with its own forces in Syria) to launch rocket attacks on Israel. The goal would be to demonstrate to Washington that what Mr Trump might see as a short punitive campaign actually risks setting the region on fire.Covert options
These range from stepped up cyber-attacks to clandestine efforts to sabotage Iranian military programmes and undermine its allies and proxies across the Middle East. But again, many of these activities have been under way for some time and we are now where we are. Iran has not been deterred, though its technical progress has almost certainly been affected.
Diplomatic responsesThis may not appear to be President Trump's "go-to" solution, but there could be some benefits in seeking to "internationalise" this crisis. This would require as detailed a presentation of the facts as possible, a kind of "name and shame" effort against Iran to try to increase its isolation.Media captionSaudi's UK ambassador says the oil facility attacks were "a blow for the world"
The difficulty here is that even the US and its key Western allies remain divided on exactly how to tackle Tehran, even if they have a broadly similar assessment of the "Iranian problem". The Europeans still hope against hope that the nuclear deal with Tehran can be preserved. Many other countries, not least Russia and China, while having no illusions about Iran, tend to see this as just a "Trump problem" and are unlikely to rally to a campaign of diplomatic maximum pressure.Of course there is another diplomatic approach that could be pursued to de-escalate things: they could try talking. Before this episode, there were various suggestions that President Trump might be open to some kind of meeting with the Iranians. That may now be even more unlikely, and it is hard to see what any Iranian leader would stand to gain domestically from such talks.