WASHINGTON — President Donald Trump's administration charged Tuesday it was "quite possible" Iran was responsible for the sabotage of Gulf oil interests but said its robust response had stopped potential attacks on Americans.

Top Trump officials appeared to be toning down weeks of fiery warnings to Iran before delivering a classified briefing to the full Congress, where opposition Democrats have accused the administration of hyping intelligence and pushing the United States dangerously close to war.

Secretary of State Mike Pompeo said the United States has not made "a definitive conclusion" that can be presented publicly over the sabotage of oil tankers off the United Arab Emirates or drone strikes on a crude pipeline in Saudi Arabia.

"But given all the regional conflicts that we have seen over the past decade and the shape of these attacks, it seems like it's quite possible that Iran was behind these," Pompeo told conservative radio host Hugh Hewitt before heading to Capitol Hill.

"Most importantly, we will continue to take acts that protect American interests and that work to deter Iran from misbehavior in the region, which has the real risk of escalating the situation such that crude oil prices rise," he said.

Yemen's Houthi rebels, who are allied with Iran and are being hit hard by US-backed Saudi air strikes, claimed responsibility last week for a drone strike on a major east-west pipeline in the kingdom, which was forced to shut down temporarily.

John Bolton, Trump's hawkish national security advisor, earlier this month warned of "unrelenting force" if Iran strikes US interests as he announced the deployment to the region of an aircraft carrier strike group, followed by nuclear-capable B-52 bombers.

Acting Defense Secretary Patrick Shanahan, who was joined at the briefing by the US military chief, Gen. Joseph Dunford, said the US response had made an impact.

"I think our steps were very prudent and we've put on hold the potential for attacks on Americans," Shanahan told reporters.

"I'd say we're in a period where the threat remains high and our job is to make sure that there is no miscalculation by the Iranians," he said.

Iranian Foreign Minister Mohammad Javad Zarif warned that the United States was "playing a very, very dangerous game" with military deployments.

"There will be painful consequences for everybody (if) there is an escalation against Iran, that's for sure," he said," Zarif told CNN.

Trump last year pulled out of a multinational agreement negotiated under his predecessor Barack Obama under which Tehran drastically scaled back its nuclear work in return for promises of sanctions relief.

The administration instead vowed "maximum pressure" to weaken Iran's regional influence, including by trying to stop all oil sales by Tehran.

Democrats said they were determined to hold the administration to account after the debacle over intelligence before the 2003 invasion of Iraq.

Entering the classified briefing, Representative Eliot Engel, the Democrat who runs the House Foreign Affairs Committee, said the administration should "inform the Congress why we seem to be walking towards war."

"I think we should have learned our lesson. War is the last thing you do, not the first thing you put on the table," he told reporters.

Democratic Senator Tim Kaine said that a new war in the Middle East would be "absolute lunacy" and, while criticizing Iran, said its actions were in line with predicted responses to Trump's moves.

"Bluntly, I believe the path to the current level of tension began when President Trump unilaterally walked out of a diplomatic deal," Kaine said Monday on the Senate floor.

Trump stoked the fire on Sunday in a tweet in which he warned: "If Iran wants to fight, that will be the official end of Iran."

But the US president — who made similar threats against North Korea before meeting leader Kim Jong Un — downplayed the Iranian threat to US interests a day later and has called for talks.

Few expect Iran's leaders to meet Trump. But Zarif has proposed a swap of prisoners, a step some observers say could offer a path to resume at least low-level dialogue to ease tensions.

Pompeo said in the radio interview, without further explanation, that there had been "just a hint" that Iran was moving to release imprisoned US citizens.

"Even a small confidence-building measure is a good thing, so it's absolutely the case that were they to release these Americans who are wrongfully held, it would be a good thing," Pompeo said. — AFP