AL-ASAD AIRBASE, Iraq — The U.S. has started to reduce the number of its troops in Iraq following Baghdad's declaration of victory over the Islamic State group last year, an Iraqi government spokesman and Western contractors said Monday.

The move marks a shift in priorities for the U.S. following the collapse of the extremists' so-called caliphate late last year. It also comes about three months ahead of Iraqi national elections in which paramilitary groups with close ties to Iran are set to play a decisive role.

Dozens of U.S. soldiers have been transported from Iraq to Afghanistan on daily flights in the past week, along with weapons and equipment, the contractors said.

An Associated Press reporter at the Al-Asad base in western Iraq saw troop movements reflecting the account by contractors. The contractors spoke on condition of anonymity in line with regulations and declined to reveal the exact size of the drawdown.

"The battle against Daesh has ended, and so the level of the American presence will be reduced," said government spokesman Saad al-Hadithi, who used the Arabic language acronym for IS.

Al-Hadithi stressed that the drawdown — the first since the war against IS began more than three years ago — was still in its early stages and doesn't mark the beginning of a complete pullout of U.S. forces.

"Continued coalition presence in Iraq will be conditions-based, proportional to the need and in coordination with the government of Iraq," Army Col. Ryan Dillon, a coalition spokesman, told the AP.

One senior Iraqi official close to Prime Minister Haider al-Abadi said 60 percent of all U.S. troops still in Iraq will be withdrawn, according to the initial agreement reached with Washington. The plan would leave about 4,000 U.S. troops to continue training the Iraqi military. The official spoke on condition of anonymity because he was not authorized to talk to the media.

As of late September, there were 8,892 U.S. troops in Iraq, according to a Pentagon report released in November.