Barack Obama
President Barack Obama says force is necessary to counter the 'grave threat' of Isis Reuters

US President Barack Obama has asked Congress to formally authorise the use of military force against the Islamic State (Isis) group for a period of three years without geographical boundaries.

Obama sent a joint resolution to lawmakers, arguing the use of force is necessary to counter the jihadist group as it "poses a grave threat to the people and territorial integrity of Iraq and Syria, regional stability, and the national security interests of the United States and its allies and partners", according to a draft copy of the text.

In an accompanying letter, the president cited IS brutality and the murders of American hostages to urge congressmen to "show the world we are united in our resolve to counter the threat".

Obama is expected to illustrate the request speaking from the White House this afternoon (11 February), a day after 26-year-old US humanitarian worker and IS Kayla Mueller was confirmed dead after being held hostage by IS.

The draft resolution asks for a three year mandate, with the duty for the president to report to Congress at least once every six months.

No geographical limits are laid out regarding where US forces can target IS and its affiliates, leaving open the door for possible operations outside Syria and Iraq.

The document however rules out the use of ground forces for "enduring offensive ground combat operations".

"The authorisation I propose would provide the flexibility to conduct ground combat operations in other more limited circumstances, such as rescue operations involving US or coalition personnel or the use of special operations forces to take military action against Isil leadership," Obama said, using another acronym for the group.

The resolution seeks a bipartisan approval of the ongoing campaign against the Islamist militants, which was authorised by Obama without prior congressional permission.

The White House had argued that congressional authorisations used by President George W Bush to justify military action after 9/11 were sufficient for him to launch air strikes in Iraq and Syria and deploy some 2,700 troops to train Iraqi security forces.

Below is the full text of the draft resolution sent to Congress: