On Sunday, the Iraqi parliament voted to expel foreign troops from the country in the wake of the killing of Iran's top military commander Qasem Soleimani in Baghdad. The government said it was working to implement the legislature's decision.

"If they do ask us to leave, if we don’t do it in a very friendly basis, we will charge them sanctions like they’ve never seen before ever. It’ll make Iranian sanctions look somewhat tame," Trump told reporters on board Air Force One, as quoted by CNBC.

"We have a very extraordinarily expensive airbase that’s there. It cost billions of dollars to build. Long before my time. We’re not leaving unless they pay us back for it," Trump added.