BAGHDAD/WASHINGTON－The United States has no plans to pull its troops out of Iraq, US Defense Secretary Mark Esper said on Monday, following media reports of a Pentagon letter informing Iraqi officials about repositioning troops in preparation for leaving the country.

Longtime foes Teheran and Washington have been in a war of words since Friday, when a drone strike ordered by US President Donald Trump killed Iranian military commander Qasem Soleimani.

Supreme Leader Ayatollah Ali Khamenei, 80, wept in grief along with hundreds of thousands of mourners who thronged the streets of Teheran for Soleimani's funeral on Monday.

Iran's demand for US forces to withdraw from the region gained traction on Sunday when Iraq's Parliament passed a resolution calling for all foreign troops to leave the country.

The Pentagon letter said US-led coalition forces would use helicopters to evacuate. Several were heard flying over Baghdad on Monday night, although it was not immediately clear if that was related.

"There's been no decision whatsoever to leave Iraq," Esper told Pentagon reporters, adding there were no departure plans issued.

"I don't know what that letter is ... We're trying to find out where that's coming from, what that is. But there's been no decision made to leave Iraq. Period," Esper said.

The letter caused confusion about the future of US forces in Iraq, who now number 5,000. A US-led invasion in 2003 toppled President Saddam Hussein.

The top US military officer told reporters the letter was a draft document meant only to underscore increased movement by US forces. "Poorly worded, implies withdrawal. That's not what's happening," said Army General Mark Milley, chairman of the military's Joint Chiefs of Staff.

The authenticity of the letter, addressed to the Iraqi Defense Ministry's Combined Joint Operations, had been confirmed by an Iraqi military source.

Esper said Washington was still committed to countering the Islamic State terror group in Iraq, alongside allies and partners.

Iraqi caretaker Prime Minister Abdel Abdul Mahdi on Monday told Matthew Tueller, the US ambassador to Baghdad, that the two nations needed to implement the Iraqi parliamentary resolution, according to a statement released by the premier's office. It did not give a timeline.

The killing of Soleimani has prompted fears around the world of a broader regional conflict, as well as calls in the US Congress for legislation to keep Trump from going to war against Iran.

The Iraqi Foreign Ministry said that US attacks "constitute a serious violation of Iraqi sovereignty and violate the conditions for the presence of the American forces in Iraq".

Esper, Milley and other top US officials agreed to provide a classified briefing for US senators on Wednesday to discuss events in Iraq after some lawmakers accused the White House of risking a broad conflict without a strategy.

Agencies - Xinhua