Iraqi popular forces have pledged to combat any US troops deployed to the conflict-hit Western Asian country.

Iraq's Kata’ib Hezbollah group, Badr Movement and Asaib Ahl al-Haq (The League of the Righteous) group made the announcement on Tuesday.

"We will chase and fight any American force deployed in Iraq. Any such American force will become a primary target for our group. We fought them before and we are ready to resume fighting," said Jafaar Hussaini, spokesman for the Kata’ib Hezbollah group.

The remarks came hours after US Defense Secretary Ashton Carter said that Washington will deploy special operations forces to fight the Takfiri Daesh terrorists in Iraq, with the ability to conduct raids over the border in neighboring Syria.

US Secretary of Defense Ashton Carter listens during a hearing of the House Armed Services Committee on Capitol Hill December 1, 2015 in Washington, DC. (AFP Photo)

"These special operators will over time be able to conduct raids, free hostages, gather intelligence, and capture ISIL (Daesh) leaders," Carter said.

Since September 2014, the US along with some of its allies has been conducting air raids against what are said to be the Daesh terrorists inside Syria without any authorization from Damascus or a UN mandate.

The air assaults in Syria are an extension of the US-led aerial campaign against purported Daesh positions in Iraq, which started in August 2014. Analysts say the attacks have failed to disband the extremists.

The foreign-backed militancy in Syria, which flared in March 2011, has left over 250,000 people dead.

Gruesome violence has also plagued some parts of Iraq ever since Daesh elements launched an offensive in June 2014, and took control of portions of Iraqi territory.

The Takfiri militants have been committing vicious crimes against all ethnic and religious communities in Iraq, including Shias, Sunnis, Kurds, Christians and others in the ares under their control.