The U.S. military said on Wednesday that all American troops had left Iraq.

This ends a 12-year mission against the Islamic State group.

The last troops left an air base in northern Iraq.

This was part of a deal between Baghdad and Washington.

President Donald Trump called the withdrawal "orderly."

It was finished by a Sept. 30 deadline.

He said the U.S. had been pulled into a "quagmire."

He said the move was a victory for the U.S., Iraq and over the Islamic State group.

The withdrawal was agreed two years ago.

It comes during the war between the United States and Iran.

That war has sometimes spilled into Iraq.

Iran-backed militias have fired on U.S. troops.

The U.S. has struck their strongholds.

Trump compared his decision to start the Iran war to the Iraq war.

He said his one-day action in Venezuela and the Iran war took less time.

He said they also caused fewer U.S. troop deaths.

Baghdad called the end of the U.S. mission a sign of its growing strength.

Iran-backed groups also celebrated.

But some Iraqis fear the Islamic State group will come back.

This is especially true in the Kurdish region.

They also fear more attacks by Iran-linked groups.

Pentagon spokesperson Sean Parnell said troops and equipment had finished an "orderly departure" from the Irbil air base.

He said the U.S. would keep giving training and intelligence support to Iraqi partners.

Iraqi Prime Minister Ali al-Zaidi led the handover ceremony.

He called the withdrawal the start of a "new phase."

He said this new phase is about Iraq's sovereignty.

He said Iraqi forces would keep fighting the Islamic State group.

He said non-state groups would no longer hold weapons.

Trump praised al-Zaidi.

He said he had endorsed him, though al-Zaidi was not on a ballot.

U.S. troops invaded Iraq in 2003.

They left in 2011.

They returned in 2014 to fight the Islamic State group.