LEON PANETTA: "We cannot allow terrorists to have safe havens from which they launch attacks and kill our forces. We cannot allow that to happen, and we have to bring pressure on the Pakistanis to do their part to confront that issue."

Relations have worsened since the killing of Osama bin Laden at his home in Pakistan earlier this year.

Michael O’Hanlon is with the Brookings Institution in Washington.

MICHAEL O’HANLON: "I think Pakistan is just going to have to wake up and smell the roses that this is not consistent with an ongoing relationship in which the United States provides three and a half billion dollars a year in aid."

Jeffrey Dressler works for the Institute for the Study of War, another research group. He says Pakistan needs the help of militant groups to limit the possible influence of India in Afghanistan.

JEFFREY DRESSLER: “They know that they would lose in a conventional war with India, and so, rather than trying to compete on that front, which they cannot, they will instead use extremist proxy groups that can sort of wage a guerrilla war.”

On Friday, the White House press secretary said Pakistan must break any links it has with the Haqqani network.

Pakistani officials reject the American accusations. They say Pakistan is cooperating with the United States against militants. Pakistani Foreign Minister Hina Rabbani Khar said the United States risks losing Pakistan as a partner if it continues to make such accusations. She spoke on Pakistan’s Geo TV.