US President Joe Biden is set to host Iraq's Prime Minister Mustafa al-Kadhemi at the White House on Monday, and Kadhemi is expected to push for a concrete timetable of foreign troop withdrawal.

On Thursday Mara Karlin, Acting Assistant Secretary of Defense for International Security Affairs, hosted Iraqi National Security Advisor Qassem al-Araji and a military delegation, Pentagon spokesman John Kirby said in a statement.

Both sides "reaffirmed the importance of the US-Iraq bilateral security relationship" as well as "the long-term US-Iraq security cooperation partnership and areas for cooperation beyond counterterrorism."

Secretary of Defense Lloyd Austin joined the group to reaffirm his support for "the US-Iraq strategic partnership."

Talks are set to resume on Friday.

Some 3,500 foreign troops are in Iraqi territory, including 2,500 Americans, who have been posted to help fight the Islamic State group since 2014.

The implementation of their withdrawal could take years.

Iraq, long an arena for bitter rivalry between the United States and Iran despite their shared enmity towards the IS, has seen growing numbers of rocket and drone attacks on US targets in recent months.

Last week Iraq's leader met with visiting US envoy Brett McGurk in Baghdad to discuss foreign troop withdrawal, his office in statement.