"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 Sunday while onboard the Air Force One.
"We have a very extraordinarily expensive air base that's there. It costs billions of dollars to build... We're not leaving unless they pay us back for it," he added.
Trump's warning came hours after the Iraqi Parliament earlier on Sunday passed a draft law requiring the government to end the presence of foreign forces and prevent them from using Iraqi air and water space, reports Xinhua news agency.
Iraqi caretaker Prime Minister Adel Abdul Mahdi attended the televised Parliament session and addressed the lawmakers, saying that "the departure of the US forces from Iraq will be in the benefit of Iraq and the US, especially after the latest developments".
In response, the US State Department said that America was "disappointed" by the action taken by the Iraqi parliament.
"We strongly urge Iraqi leaders to reconsider the importance of the ongoing economic and security relationship between the two countries and the continued presence of the Global Coalition to Defeat IS (the Islamic State)," the statement said.
The Iraqi parliament session came two days after a US drone strike on a convoy near Baghdad International Airport killed Qasem Soleimani, commander of the Quds Force of Iran's Islamic Revolution Guards Corps, and Abu Mahdi al-Muhandis, deputy chief of Iraq's paramilitary Popular Mobilization Forces or Hashd Shaabi.
Over 5,000 US troops have been deployed in Iraq to support the Iraqi forces in the battles against the IS militants, mainly providing training and advising to the local forces.
( With inputs from IANS )