The Obama administration was investigating whether Pakistan knew Osama bin Laden was hiding deep inside the country as House Speaker John Boehner and top lawmakers insisted the U.S. maintain close ties with the sometimes reluctant ally in the war on terror.

The killing of Osama bin Laden at a compound just miles from Islamabad prompted furious questions about whether Pakistan was complicit in protecting the mastermind of the Sept. 11 attacks. Several Republicans and Democrats in Congress have raised the possibility of cutting off U.S. aid to Pakistan.

John Brennan, White House counterterrorism adviser, said the administration is "not accusing anybody at this point, but we want to make sure we get to the bottom of this." He said they were looking at whether bin Laden had a support system in Pakistan that allowed him to remain in the country. He made the comments in an interview with National Public Radio.

Amid the harsh criticism of Pakistan, Boehner and others said this was not the time to back away from Pakistan.

"I think we need more engagement, not less," he said. "Al-Qaida and other extremist groups have made Pakistan a target. ... Having a robust partnership with Pakistan is critical to breaking the back of al-Qaida and the rest of them."

Boehner said it was premature to talk about cutting off U.S. aid to Pakistan. When pressed on the level of funds, however, he said it was imperative that the U.S. have an "eyeball to eyeball conversation about where this relationship is going." He made the comments in an hourlong interview with a handful of reporters.

Congressional Republicans and Democrats questioned whether bin Laden was hiding in plain sight, with Pakistani military and intelligence operatives either totally unaware of his location or willfully ignoring his presence to protect him.

Bin Laden's death and questions about Pakistan's eagerness in the fight against terrorism came as the tenuous U.S.-Pakistan relationship seems even more fragile. In recent weeks, CIA contractor Raymond Davis' killing of two Pakistanis and stepped-up drone attacks further strained ties between the two countries.

Different factions within Pakistan itself complicate its role as a U.S. ally. What state officials and those in the military may have known about bin Laden could be quite different from what tribes and even families in the region knew or, more to the point, were willing to say about the Abbottabad compound and its occupants.

A frustrated Pakistan on Tuesday called the U.S. raid to get bin Laden an "unauthorized unilateral action" that "cannot be taken as a rule."

Sen. Dianne Feinstein, D-Calif., the head of the Senate Intelligence Committee, said Congress may consider cutting the almost $1.3 billion in annual aid to Pakistan if it turns out the Islamabad government knew where bin Laden was hiding.

The No. 2 House Democratic leader, Rep. Steny Hoyer of Maryland, said if Pakistan doesn't ease doubts about its dedication to fighting terrorists, Congress should explore whether it makes sense to reduce U.S. aid to that country.

"I don't know whether it would be effective or counterproductive, we'll have to look at that," he told reporters, adding, "It needs to be looked into."

Sen. Lindsey Graham, R-S.C., a member of the Senate Armed Services Committee, acknowledged the frustration of his colleagues.

"But at the end of the day, if you want to create a failed state in Pakistan, one of the best things to do is sever relationships. It is not in our national security interest to let this one event destroy what is a difficult partnership but a partnership nonetheless," Graham said.

The Obama administration pushed back on talk of punishing Pakistan.

White House spokesman Jay Carney told reporters Tuesday that the U.S. is committed to cooperating with Pakistan despite questions about who in the Islamabad government may have known that bin Laden was in hiding in his compound in Abbottabad.

"We don't know who if anybody in the government was aware that bin Laden or a high-value target was living in the compound. It's logical to assume he had a supporting network. What constituted that network remains to be seen," Carney said. "It's a big country and a big government and we have to be very focused and careful about how we do this because it is an important relationship."

State Department spokesman Mark Toner said the U.S. aid "is in both Pakistan's long-term interests as well as the United States' national interests and security interests."

Prior to the raid on the compound, U.S. officials say, they didn't inform Pakistan of U.S. plans. Unaware and unnerved Pakistanis scrambled their aircraft in the wake of the U.S. military intervention.

Publicly, Secretary of State Hillary Rodham Clinton thanked Pakistan for its cooperation and said the country "has contributed greatly to our efforts to dismantle al-Qaida." She said that "in fact, cooperation with Pakistan helped lead us to bin Laden and the compound in which he was hiding."

Sen. Bob Corker, R-Tenn., a member of the Foreign Relations Committee, sent a letter to Clinton seeking details on the level of cooperation from Pakistan, saying the fact that bin Laden lived in comfortable surroundings near Islamabad "calls into question whether or not the Pakistanis had knowledge that he was there and did not share that knowledge."

In an essay published Tuesday by The Washington Post, Pakistani President Asif Ali Zardari denied suggestions his country's security forces may have sheltered bin Laden, and said their cooperation with the United States helped pinpoint his location.


Associated Press writers Kathy Gannon and Nahal Toosi in Pakistan and Alan Fram and Kimberly Dozier in Washington contributed to this report.