Pentagon chief says anti-IS fight may take longer than 3 yrs

U.S. Defense Secretary Ashton Carter said on Wednesday that the fight against the extremist group "Islamic State" (IS) may take longer time than the three- year timeline stipulated in U.S. President Barack Obama's force authorization request.

"I cannot tell you that our campaign to defeat ISIL would be completed in three years," Carter told the U.S. Senate Foreign Relations Committee in his first hearing on Obama's war authorization request to Congress, using another acronym for the militant group.

On Feb. 11, the Obama administration unveiled its war authorization bill against the IS that would prohibit the use of " enduring offensive ground forces" and limit engagement to three years.

Carter said though he was uncertain whether the task could be finished within three years, the provision was "sensible and principled."

"The president's proposed authorization affords the American people the chance to assess our progress in three years time, and provides the next president and the next Congress the opportunity to reauthorize it, if they find it necessary," he said.

Under the authorization for the use of force passed in 2001, Obama administration could use force to go after the extremist group Al-Qaida and its affiliates, namely Islamic State (IS) in this case, without permission from Congress.

U.S. Secretary of State John Kerry, another witness at Wednesday's hearing, said the purpose for seeking formal force authorization was to show a united America in this effort.

"A clear and careful expression of this Congress' backing at this point and time would expel doubt that might exist anywhere that Americans are united in this effort," Kerry said.

However, the Obama administration's war authorization pitch is expected to undergo major changes in its language at best, as hawkish Republicans said the restraints of Obama's bill would handcuff the military while Democrats demanded clearer language in prohibiting a large U.S. ground combat presence. The worst scenario would be inaction from the Congress.

During his hearing session, Kerry was interrupted several times by anti-war protesters who yelled repeatedly that U.S. campaign against IS would lead to the death of "innocent people." Endite