*Americans to stay in Iraq
*Soleimani was planning imminent attack: Esper
US Defence Secretary Mark Esper said Tuesday that the Pentagon fully expects that Iran will retaliate for the killing of Islamic Revolutionary Guards commander Qasem Soleimani in a Baghdad drone strike last week.
"I think we should expect they will retaliate in some way, shape or form," Esper told reporters.
Esper said it was "more than fair to say" the attack that Iranian military commander Qassem Soleimani was planning was to be executed in days rather than weeks.
Speaking to reporters just days after the killing of Soleimani in a US airstrike in Baghdad, Esper said Washington is seeking a diplomatic solution with Iran but that Tehran needs to de-escalate.
US President Donald Trump told reporters Tuesday he would obey international law on avoiding targeting cultural sites in military attacks, walking back a threat he made to Iran days earlier.
Trump on Saturday said the United States has targeted 52 Iranian sites, including ones that are very important to Iranian culture, and would strike if Iran attacks Americans or US assets in response to the US killing of Soleimani.
Meanwhile, Iraq's premier Adel Abdel Mahdi confirmed Tuesday that he had received what the US said was a draft letter describing steps its military would take to "move out" of Iraq.
The Pentagon had said an unsigned draft version of the letter had been mistakenly sent, but the Iraqi premier disputed that claim.
In a televised cabinet meeting in Baghdad, Mahdi said he had received signed and translated copies at 8pm local time Monday.
However, Esper said the United States is not pulling its forces out of Iraq, denying that there is a signed letter from the US side announcing an exit.
"Our policy has not changed. We are not leaving Iraq," Esper told reporters.
"There is no signed letter, to the best of my knowledge."
Trump said that a US troop withdrawal from Iraq at this stage would be the "worst thing" for the country.
"At some point we want to get out, but this isn't the right point," Trump said. "It's the worst thing that could happen to Iraq.