Central Command chief General Kenneth McKenzie said the carrier groups would be staying for a sustained period following a series of attacks on US positions in Iraq by Iranian-backed groups that have ratcheted up tensions with Tehran.

Early Friday the US military launched air strikes against weapons depots of Kataeb Hezbollah, an Iraqi armed faction backed by Iran.

The strikes, by manned aircraft, were in retaliation for a Wednesday rocket attack attributed to Kataeb Hezbollah that killed two American soldiers and a British soldier at Iraq's Taji air base.

"We are confident that we have effectively destroyed these facilities and expect they will no longer be able to house the type of advanced Iranian supplied weapons that were used in the Kataeb Hezbollah attacks on the Iraq base at Camp Taji," he told a news conference, showing journalists before and after surveillance photographs.

- Proxy attacks -

McKenzie accused Tehran of continuing to support attacks against US and coalition forces via its proxies in Iraq.

"I think the threat remains very high. I think that tensions have actually not gone down," McKenzie said.

"I would caution Iran and its proxies from attempting a response that would endanger US and coalition forces," he said.

The deployment of the USS Dwight D. Eisenhower and the USS Harry S. Truman marked the first time since 2012 that the Pentagon had authorized keeping aircraft carriers in the Gulf.

"We have the flexibility, the capability and the will to respond to any threat," McKenzie said.

"There are no access, basing and overflight issues associated with an aircraft carrier. It's a floating piece of American sovereignty," he said.

- Soleimani 'missed' by Tehran -

McKenzie said Tehran had not pulled back its regional military operations since the US killing in January of Qasem Soleimani, the top Iranian general who directed operations against US forces and managed Tehran's proxies.

He added however that its ability to direct groups like Kataeb Hezbollah had been diminished by the loss of Soleimani and the impact of the coronavirus pandemic on the Iranian leadership.

"It's harder for them to make effective decisions... Someone has replaced him. I don't think that someone is going to be as good as him in the short term. We'll see how it works out in the long term," McKenzie said.

The US does not believe Iran wants a direct conflict, preferring instead to continue to act through proxies to harass American forces and promote its own ideology in the region.

"We believe we have established a level of state-to-state deterrence, in that Iran does not seek a large scale military exchange with the United States," McKenzie said.

But he added: "None of their core objectives have changed."