The U.S. Chairman of the Joint Chiefs of Staff, Adm. Michael Mullen, told the Senate hearing that although the relationship with Pakistan is complicated, not dealing with the Pakistanis would likely mean the U.S. would be out of the picture in Pakistan -- where the Afghan Taliban regrouped after 9/11 -- for another five to 10 years.
He added that the U.S. is in the midst of building a relationship with Pakistan, which was "badly broken" in the '80s and '90s.
Mullen said that "some of the criticism is more than warranted" when it comes to the relationship with Pakistan.
"Nobody's worked that harder than me, very frankly, with the leadership -- and it's a conscious decision, I think, that we have to make," he said. "If we walk away from it, it's my view it'll be a much more dangerous place a decade from now, and we'll be back."
ABC News' Kristina Wong and Luis Martinez contributed to this report.