As US forces strike Syrian militias backed by Tehran, many fear delegation to the Pentagon and the looming defeat of the Islamic State could fuel a fiercer fire
US forces have opened fire on Iranian-backed forces in Syria three times in the past month, amid mounting tensions that observers and former officials worry could easily turn into an unplanned, spiralling conflict.
The three recent incidents took place at al-Tanf, a remote desert outpost near the point where the Syrian, Iraqi and Jordanian borders meet. There, a 150-strong force of US soldiers who are training local fighters to take on the Islamic State (Isis) was approached by convoys of militias fighting for the Assad regime. They responded with air strikes.
The encroaching forces seem to have been a mix of Syrian and Iraqi Shia militias, possibly accompanied by their chief sponsor, Irans Islamic revolutionary guard corps (IRGC).
Certainly the IGRC was not concerned about hiding its fingerprints. The commander of its Quds force, Qassem Soleimani, had himself photographed with militia forces nearby and a drone shot down by US forces after it had dropped a bomb near them turned out to be Iranian-made.
The string of incidents has illustrated how the eastern Syrian desert is becoming an arena for confrontation between the US and Iran, a potential flashpoint alongside Yemen, where Washington and Iran back opposing forces in a two-year war, and the Gulf around the Strait of Hormuz.
Last Wednesday an Iranian navy vessel came within 800 yards of a US flotilla traveling through the strait, shining spotlights on the US ships and pointing a laser at a helicopter in an encounter US military officials described as unprofessional and dangerous.
Such encounters are not new in the busy Hormuz waterway, but the context for them is. There is a new administration in Washington that is in many ways chaotic, but is united on a desire to push back Iranian influence in the region. Internal opinion differs mainly on the degree of force and risk required.
High-level contacts established between Washington and Tehran by the Obama administration have been cut off. From the White House, Donald Trump has maintained the fervently anti-Iranian rhetoric of his campaign. He made the first foreign trip of his presidency to Saudi Arabia, siding unambiguously with Riyadh in its rivalry with Tehran.
Trump has portrayed Iranian influence as a global threat on a par with Isis and al-Qaida. When Tehran suffered a terrorism attack on 7 June, the US president implied that the Iranian government was ultimately to blame.
We underscore that states that sponsor terrorism risk falling victim to the evil they promote, he said in a White House statement.
Trita Parsi, head of the National Iranian American Council, this month published a book, Losing an Enemy: Obama, Iran and the Triumph of Diplomacy.
By going to Saudi Arabia and declaring there was going to be an all-out isolation of Iran, he said not only did Trump close the window for an all-inclusive dialogue, but he also opened up a window for a potential war with Iran.
There is no debate in the country about this. It may have the appearance of being accidental but if youre following it closely you see it is a very deliberate escalation.
Trump has not delivered on his campaign threat to dismantle the nuclear deal with Iran agreed by the Obama administration and five other major powers in July 2015, but he has continued to pour contempt on it while Republicans in Congress have pushed for new sanctions that would put the agreements survival in jeopardy.
Three of the most dangerous places on earth today are in Yemen, the area between eastern Syria and western Iraq and the halls of the US Congress, said Robert Malley, a senior Obama White House official who helped negotiate the nuclear deal.
At this point what Im hearing from the Iranians is they are determined to play it cool, not overreact to what the US does, and show they are the ones who are being fully compliant. At some point, it may well be the supreme leader decides: We are going to do something.
The Trump administration says it is still reviewing Iran policy but secretary of state Rex Tillerson told the Senate last week the US would work toward support of those elements inside of Iran that would lead to a peaceful transition.
You can see it all going haywire
The emphasis was on peaceful change but to Iranian government ears, that sounded like a reversion to the spirit of regime change of the Bush era and even more distant memories, of a CIA-engineered coup in 1953. Tillersons counterpart, Mohammad Javad Zarif, tweeted back a jab about the shadow of the Russia investigations hanging over the Trump presidency: For their own sake, US officials should worry more about saving their own regime than changing Irans, where 75% of people just voted.
There is growing concern among US allies in Europe that the Trump administration has struck a posture towards Iran before deciding on a strategy for addressing its influence in the region, and anxiety that such posturing could become louder and more dangerous as Trump feels hemmed in by investigations into his campaigns Russia links.