Central Intelligence Agency Director Leon Panetta testifies during a confirmation hearing before the Senate Armed Services Committee on Capitol Hill. (Win McNamee/GETTY IMAGES)

The presumptive new leader of the Pentagon, Leon E. Panetta, offered almost no specifics at his Senate confirmation hearing Thursday on how he’ll oversee the war in Afghanistan, saying it was up to others in the Obama administration to decide how many troops to begin withdrawing next month.

Panetta, 72, is scheduled to take office in three weeks assuming he wins Senate approval. That seemed a safe bet Thursday as members from both parties on the Senate Armed Services Committee praised his record as director of the CIA since 2009, particularly his handling of the daring raid that killed al-Qaeda leader Osama bin Laden in Pakistan. “I can’t wait to vote for you!” gushed Sen. Lindsey O. Graham (R-S.C.).

At the same time, the gentle grilling that the senators gave Panetta made clear that running the Defense Department will be far tougher than getting confirmed. The tenor of the questions indicated that his honeymoon period could be brief as he faces pressure to wind down the wars in Afghanistan, Iraq and Libya, as well as manage pending cuts to the Pentagon’s budget. President Obama has ordered $400 billion in spending reductions on national security over the next 12 years, and it will be largely up to Panetta, a longtime budget expert in Washington, to figure out the details.

Panetta was especially cautious in describing his views about the Afghan war, repeating stock comments from the administration that the U.S. military had made gains but that they were “fragile and reversible.”

He said he agreed with Obama that troop withdrawals starting next month should be “significant.” But he dodged attempts by Sen. John McCain (R-Ariz.) to pin him down, saying that it was up to Obama, current Defense Secretary Robert M. Gates and Gen. David H. Petraeus, the U.S. commander in Afghanistan, to decide on specific numbers.

He did allow that bin Laden’s death could mark a turning point in the long-running fight against al-Qaeda.

“It’s given us the greatest chance since 9/11 to disrupt, dismantle and defeat al-Qaeda,” Panetta said. “But to do that, to be able to finish the job, we’ve got to keep the pressure up.”

Later, he added: “I think the fundamental mission in Afghanistan is to provide sufficient stability so that that country never again becomes a safe haven for al-Qaeda or al-Qaeda’s militant allies.”

But several Democrats and Republicans indicated that their patience was wearing thin. Sen. Susan Collins (R-Maine) called the Afghan war “a never-ending mission.”

“I don’t see how we get to a stable state in Afghanistan,” she said. “So tell me how this ends. I just don’t see how it ends.”

Panetta paused and then responded that he was once very pessimistic about the war in Iraq but that things had turned around there. “If we stick with it,” he said, “there is going to be a point where Afghanistan can control its own future. I think we have to operate on that hope.”

The former Democratic congressman from California was more forthcoming about other global trouble spots. He said U.S. forces were still actively engaged in counterterrorism operations in Yemen, home to a thriving al-Qaeda affiliate, despite the political chaos and violence that has gripped the Arab country. U.S. aircraft have carried out two airstrikes against suspected al-Qaeda targets in Yemen in recent weeks, and U.S. counterterrorism trainers remain in the country.

“It’s been destabilized, and yet we are continuing to work with those individuals in their government to try to go after AQAP,” Panetta said, referring to the group known as al-Qaeda in the Arabian Peninsula.

Regarding the war in Libya, Panetta said that the NATO-led mission was proving effective and predicted that it would eventually force Moammar Gaddafi from power. “If we continue the pressure, if we stick with it, I think ultimately Gaddafi will step down,” Panetta said.

But some senators expressed their doubts about that outcome.

“If there’s any painful lesson that we have learned from our experience in Iraq, it is that if we do not have a plan in place after we have deposed a tyrant, that chaos and violence ensues,” Collins said. “Do you have confidence that we have a plan for dealing with Libya post-Gaddafi?”

Panetta replied that it was a “legitimate concern,” but he said: “I’m confident that there are enough leaders in the opposition who can provide, hopefully, that continuity.”