Iran has chosen to “step back and recalculate” after making preparations for an apparent attack against US forces in the Gulf region, but it is too early to conclude the threat is gone, the top commander of American forces in the Mideast said on Thursday.

In an interview with three reporters accompanying him to the Gulf, General Frank McKenzie, the head of US central command, said he remained concerned by Iran’s potential for aggression, and he would not rule out requesting additional US forces to bolster defences against Iranian missiles or other weapons.

“I don’t actually believe the threat has diminished,” McKenzie said. “I believe the threat is very real.”

Tensions between the US and Iran have worsened since Donald Trump withdrew from a 2015 nuclear agreement between Iran and several world powers, and reinstated sanctions on Tehran. Last month, in response to what American officials characterised as an imminent threat, the US announced it would rush an aircraft carrier and other assets to the region.

The US also blamed Iran for last month’s attacks on oil tankers in a United Arab Emirates port.

On Thursday, United Nations ambassadors from the Emirates, Saudi Arabia and Norway told UN security council members that investigators believe those attacks were led by a foreign state using divers on speed boats who planted mines on the vessels. They did not name Iran.

Earlier, the Saudi ambassador to the UN, Abdallah Al-Mouallimi, said Saudi Arabia also blamed Iran for the sabotage.

In Baghdad, McKenzie told reporters that US redeployments to the Gulf have “caused the Iranians to back up a little bit, but I’m not sure they are strategically backing down.”

The general said the US is showing enough force to “establish deterrence” without “needlessly” provoking its longtime adversary. “We’re working very hard to walk that line.”

He said: “We’ve taken steps to show the Iranians that we mean business in our ability to defend ourselves,” referring to the accelerated deployment to the Gulf area of the USS Abraham Lincoln carrier strike group, four Air Force B-52 bombers and additional batteries of Army Patriot air-defence systems.

Trump, speaking beside French president, Emmanuel Macron, in French city of Caen, France, said US sanctions were crippling Iran’s economy, possibly yielding a diplomatic opening.

“And if they want to talk, that’s fine,” the US president Trump said. “We’ll talk. But the one thing that they can’t have is they can’t have nuclear weapons.”

Speaking at the Baghdad headquarters of the US-led coalition fighting the Islamic State group in Iraq and Syria, McKenzie said he also has repositioned surveillance aircraft to more closely monitor the situation in the Gulf and in Iraq, where the U.S. has 5,200 troops on the ground, and has given Iran a “new look” by introducing more aerial patrols by land- and carrier-based fighters.

“Cumulatively, all of these have caused them to sort of step back and recalculate the course that they apparently were on,” he said.