Donald Trump / REUTERS

U.S. President Donald Trump threatened sanctions against Baghdad on Sunday after Iraq's parliament called on U.S. troops to leave the country, and the president said if troops did leave, Baghdad would have to pay Washington for the cost of the air base there.

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"We have a very extraordinarily expensive air base 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 told reporters on Air Force One, as reported by Reuters.

Trump said that if Iraq asked U.S. forces to leave and it was not done on a friendly basis, "we will charge them sanctions like they've never seen before ever. It'll make Iranian sanctions look somewhat tame."