The two missile strikes on training camps run by Baitullah Mehsud represent a broadening of the American campaign inside Pakistan, which has been largely carried out by unmanned drone aircraft. Under President George W. Bush, the United States frequently attacked militants from al-Qaida and the Taliban involved in cross-border attacks into Afghanistan, but had stopped short of raids aimed at Mehsud and his followers, who have played less of a direct role in attacks on American troops.

Strikes continue

The strikes are another sign that President Barack Obama is continuing Bush administration policy in using the military and intelligence agencies against suspected terrorists in Pakistan, as he had promised to do during his presidential campaign. At the same time, Obama has begun to scale back some of the Bush policies on the detention and interrogation of terror suspects, which he has criticized as counterproductive.

Mehsud was identified early last year by both American and Pakistani officials as the man who orchestrated the assassination of Benazir Bhutto, the former prime minister and the wife of Pakistan’s current president, Asif Ali Zardari. Bush included Mehsud’s name in a classified list of militant leaders whom the CIA and American commandos were authorized to capture or kill.

It is unclear why the Obama administration decided to carry out the attacks, which American and Pakistani officials said occurred last Saturday and again on Monday, hitting camps run by Mehsud’s network. The Saturday strike was aimed specifically at Mehsud, according to Pakistani and American officials. The Monday strike, officials say, was aimed at a camp run by Hakeem Ulah Mehsud, a top aide to the militant.

By striking at the Mehsud network, the United States may be seeking to demonstrate to Zardari that the new administration is willing to go after the insurgents of greatest concern to the Pakistani leader. But American officials may also be prompted by growing concern that the militant attacks are increasingly putting the civilian government of Pakistan, a nation with nuclear arms, at risk.

Mehsud a target

For months, Pakistani military and intelligence officials have complained about Washington’s refusal to strike at Mehsud, even while CIA drones struck al-Qaida figures and leaders of the network run by Jalaluddin Haqqani, a militant leader believed responsible for a campaign of violence against American troops in Afghanistan.

According to one senior Pakistani official, Pakistan’s intelligence service on two occasions in recent months gave the United States detailed intelligence about Mehsud’s whereabouts, but, he said, the United States did not act on the information. Bush administration officials had charged that it was the Pakistanis who were reluctant to take on Mehsud and his network.

The strikes came after a visit to Islamabad last week by Richard Holbrooke, the American envoy to Pakistan and Afghanistan.

On Friday, Holbrooke declined to talk about the attacks on Mehsud. The White House also declined to speak about Mehsud or the decisions that led up to the new strikes.

Tension over truce

Senior Pakistani officials are scheduled to arrive in Washington next week at a time of rising tension over a declared truce between the Pakistani government and militants in the Swat region of Pakistan.

While the administration has not publicly criticized the Pakistanis, several American officials said in recent days that appeasing the militants would only weaken Pakistan’s civilian government. Holbrooke, who returned to Washington earlier this week, said that Secretary of State Hillary Rodham Clinton and others would make clear in private, and in detail, why they were so concerned about what was happening in Swat, the need to send more Pakistani forces to the West, and why the deteriorating situation in the tribal areas added to instability in Afghanistan.