Updated

President Donald Trump’s decision to recognize Jerusalem as Israel’s capital could incite extremists in the region -- making conditions "favorable to terrorism" against U.S. targets, Iraq's government warned Thursday.

Iraqi leaders in Baghdad called for Trump to reverse his decision, saying that it could threaten stability in the Middle East.

“We caution against the dangerous repercussions of this decision on the stability of the region and the world,” the government's statement said.

An Iran-backed militia operating in Iraq echoed Baghdad's statement, saying Trump’s "stupid decision" would be a “legitimate reason” to attack U.S. troops in Iraq, Reuters reported.

“Trump’s stupid decision to make Jerusalem a capital for the Zionist will be the big spark for removing this entity from the body of the Islamic nation, and a legitimate reason to target American forces,” said Akram al-Kaabi, the group's leader.

The militia, Harakat Hezbollah al-Nujaba, is composed of some 10,000 Iraqi fighters under an umbrella of Iran-backed Shi’ite militias.

Iraq has also summoned the U.S. ambassador in Baghdad and plans to hand over a memo protesting the new policy, Reuters reported.

Meanwhile, the Palestinian group Hamas -- recognized as terrorists by the U.S. -- threatened its own retaliation against Israel following Trump's declaration of the new U.S. policy, a separate Reuters report said.

"We should call for and we should work on launching an intifada in the face of the Zionist enemy," Hamas leader Ismail Haniyeh said in a speech in Gaza.

"The U.S. decision is an aggression, a declaration of war on us, on the best Muslim and Christian shrines in the heart of Palestine, Jerusalem."

Hamas has fought three wars with Israel since 2007.

"We have given instruction to all Hamas members and to all its wings to be fully ready for any new instructions or orders that may be given to confront this strategic danger that threatens Jerusalem and threatens Palestine," Haniyeh added.

Trump announced Wednesday that the U.S. would formally recognized Jerusalem as Israel's capital, saying it's time to "acknowledge the obvious" as he ordered the State Department to begin moving the U.S. Embassy from Tel Aviv to Jerusalem.