Gen. Stanley McChrystal says capturing Osama bin Laden is the key to defeating al-Qaeda. (Gerald Herbert/Associated Press)

Capturing Osama bin Laden is the key to defeating al-Qaeda, the U.S. general in charge of the war in Afghanistan told Congress on Tuesday.

Gen. Stanley McChrystal told House and Senate panels that bin Laden is an "iconic figure" whose very survival eight years after the Sept. 11 attacks on the U.S. serves as a recruiting tool for the terrorist group.

U.S. intelligence officials believe bin Laden is in Pakistan, hiding in its rugged terrain bordering Afghanistan.

Finding bin Laden would not end the war in Afghanistan, but the U.S. could never defeat al-Qaeda's terrorist network until he is caught, McChrystal said.

He also said he should know by this time next year whether the troop surge is countering Taliban momentum. He also believes he will be able to begin withdrawing forces in 2011 without requiring additional troops.

McChrystal spoke before Congress a week after President Barack Obama announced the deployment of 30,000 more soldiers to Afghanistan. McChrystal said he had not recommended Obama's 18-month term for the surge and would have preferred even more troops.

Nevertheless, the general threw his support behind the strategy.

"I'm comfortable with the entire plan, sir," McChrystal told Senator Carl Levin, chairman of the Senate armed services committee and one of the Democrats most publicly skeptical of Obama's strategy.

Closing ranks

Ambassador Karl Eikenberry, who had previously expressed apprehension, also saluted the new approach.

The two men sat side-by-side at a pair of Capitol Hill hearings long sought by politicians critical of the lengthy White House review that yielded the decision to send an emergency infusion of additional U.S. forces.

McChrystal and Eikenberry have clashed over the general's request for tens of thousands of more soldiers. In November, Eikenberry sent classified memos to Washington in which he expressed serious concern over sending more troops until Afghan President Hamid Karzai addressed the corruption in his government, according to the Washington Post.

With Obama's latest announcement, the two have appeared to close ranks. Eikenberry — who served as a commander in Afghanistan in 2006 and 2007 — tried to clarify his position Tuesday.

"I want to say from the outset that Gen. McChrystal and I are united in a joint effort where civilian and military personnel work together every day," Eikenberry said.

"It was not a question of additional troops. It was a question of the number of troops ... the timelines... the context that those troops would operate in."

While the ambassador is supporting Obama's strategy, he still expressed skepticism over how the U.S. will win the war in Afghanistan unless there is "more progress at eliminating the sanctuaries used by the Afghan Taliban and their associates inside of Pakistan."

The Taliban haven in Pakistan is considered the most troubling hole in the new war strategy, a perception echoed Tuesday by North Carolina Republican Walter Jones and New Jersey Democrat Robert Andrews.

When both politicians asked McChrystal if U.S. forces were able to pursue insurgents across the border, the general said he would have to "consult the specific rules of engagement."

U.S. officials met with the heads of Pakistan's military and intelligence services in November, urging Pakistan to ramp up efforts to fight Taliban inside its own borders.

With files from The Associated Press