The United States has publicly rebuked a senior British general who challenged claims that Iranian-backed groups are preparing to mount attacks against Western assets in the Middle East.
The extraordinary move came after Major General Chris Ghika, the deputy commander of Operation Inherent Resolve, the US-led coalition against Islamic State, said that there was no increased threat from pro-Iranian groups in Iraq and Syria.
In recent days Donald Trump's administration has said that Iran is preparing its allied and proxy forces to mount attacks on US assets across the Middle East, and has sent an aircraft carrier strike group, a squadron of B-52 bombers, and a battery of patriot missiles to the region to counter the alleged threat.
Pentagon officials have also reportedly drawn up options to send up to 120,000 additional troops in preparation for a large-scale military campaign.
But when reporters in the Pentagon asked Maj Gen Ghika about the claims on Tuesday, he said: "No, there's been no increased threat from Iranian-backed forces in Iraq and Syria."
Speaking by video-link from Baghdad, he said: "We're aware of their presence, clearly, and we monitor them, along with a whole range of others because that's the environment we're in."
He added: "I am not going to go into the detail of it, but there are a substantial number of militia groups in Iraq and Syria and we don't see an increased threat from many of them at this stage."
Hours later the US military disowned the British general's comments and directly contradicted him.
US Central Command, which is responsible for US military operations in the Middle East, claimed both US forces and their allies - including the mission Maj Gen Ghika is deputy commander of - are aware of and have responded to the threat.
"Recent comments from OIR's Deputy Commander run counter to identified credible threats available to intelligence from US and allies regarding Iranian-backed forces in the region," said Captain Bill Urban in a statement.
"US Central Command, in coordination with Operation Inherent Resolve, has increased the force posture level for all service members assigned to OIR in Iraq and Syria. As a result, OIR is now at a high level of alert as we continue to closely monitor credible and possibly imminent threats to US forces in Iraq."
The ministry of defence said: "Major General Ghika speaks as a military officer in the US-led Coalition focused on the fight against Daesh in Iraq and Syria. His comments are based on the day to day military operations and his sole focus is the enduring defeat of Daesh.
"The UK has long been clear about our concerns over Iran's destabilising behaviour in the region."
It said the general had been clear that threats exist to US and allied forces.
The exchange comes amid a growing rift between the US and its closest allies over the crisis.
Jeremy Hunt, the Foreign Secretary, this week said he was worried the US and Iran were stumbling towards armed conflict.
Donald Trump denied the reports that plans have been drawn up to send up to 100,000 troops to counter Iran if necessary, but added: "Would I do that? Absolutely."
The U.S. State Department on Wednesday said it was withdrawing all non-emergency staff from its Baghdad embassy and its consulate in Erbil. It has also issued a travel advisory warning US citizens against all travel to Iraq.
Ayatollah Ali Khamenei, Iran's supreme leader, played down the prospect of conflict on Tuesday, saying neither country wanted a war, according to state media.
But in he also reiterated Iran's threat to resume elements of its nuclear program, telling a group of officials during a meeting on Tuesday night that "achieving 20 percent enrichment is the most difficult part. The next steps are easier than this step."
Mr Trump's administration has pursued a policy of "maximum pressure" against Iran, including tightening economic sanctions, since withdrawing the US from a deal designed to limit Iran's nuclear program last year.
Iran has said it will partially suspend its own commitments under the deal and restart parts of its nuclear program, including enriching uranium, if the world does not find a way to ease the damage of US sanctions that have devastated its economy.
It has given the European Union, Britain, France, Germany, Russia and China, and Russia, the remaining signatories of the deal, 60 days to come up with a way for it to continue to sell oil and receive the revenues.
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