President Donald Trump threatened to impose deep sanctions on Iraq if it moves to expel U.S. troops and said on Sunday he would not withdraw entirely unless the military is compensated for the “extraordinarily expensive air base” there.

Trump’s comments came on the same day that Iraq’s Parliament voted to support expelling the U.S. military from its country over mounting anger about a drone strike the president ordered last week that killed Iran’s Qasem Soleimani and earlier U.S. airstrikes in the country. The vote was nonbinding.

“We’ve spent a lot of money in Iraq,” Trump told reporters aboard Air Force One as he returned to Washington after spending the holidays at his Florida resort, Mar-a-Lago. “We have a very extraordinarily expensive air base that’s there. It cost billions of dollars to build. … We’re not leaving unless they pay us back for it.”

Donald Trump and his advisers have been defending the drone attack that killed Iranian military commander Qassem Soleimani, escalating tensions in the region.

Trump says Soleimani was planning attacks against US citizens and said he would consider releasing intelligence reports that led him to direct the killing.

Asked on Air Force One about potential retaliation by Iran, Trump said: “If it happens, it happens. If they do anything, there will be major retaliation.”

Trump, who spoke to reporters on his way back to Washington from a holiday in Florida, has said Soleimani was killed to avoid war with Tehran and warned against further escalation.

But he has deployed aggressive rhetoric in public, tweeting that the US would target 52 Iranian sites, some “at a very high level & important to Iran & the Iranian culture” if Iran struck any US citizens or assets in retaliation.