U.S. Aides Believe China Examined Stealth Copter

In the days after the raid that killed Osama bin Laden, Pakistan’s intelligence service probably allowed Chinese military engineers to examine the wreckage of a stealth American helicopter that crashed during the operation, according to American officials and others familiar with the classified intelligence assessments. Such cooperation with China would be provocative, providing further evidence of the depths of Pakistan’s anger over the Bin Laden raid, which was carried out without Pakistan’s approval. The operation, conducted in early May, also set off an escalating tit-for-tat scuffle between American and Pakistani spies.

American spy agencies have concluded that it is likely that Chinese engineers — at the invitation of Pakistani intelligence operatives — took detailed photographs of the severed tail of the Black Hawk helicopter equipped with classified technology designed to elude radar, the officials said. The members of the Navy Seals team who conducted the raid had tried to destroy the helicopter after it crashed at Bin Laden’s compound in Abbottabad, but the tail section of the aircraft remained largely intact.

American officials cautioned that they did not yet have definitive proof that the Chinese were allowed to visit to Abbottabad. They said that Pakistani officials had denied that they showed the advanced helicopter technology to other foreign governments. One military official said Sunday that Pakistani officials had been directly confronted about the American intelligence.

One person with knowledge of the intelligence assessments said that the American case was based mostly on intercepted conversations in which Pakistani officials discussed inviting the Chinese to the crash site. He characterized intelligence officials as being “certain” that Chinese engineers were able to photograph the helicopter and even walk away with samples of the wreckage. The tail has been shipped back to the United States, according to American officials.

Pakistan has a close military relationship with China, and large numbers of Chinese engineers work at military bases inside Pakistan. Pakistani officials have even suggested that the Chinese Navy might eventually have its own base along Pakistan’s coastline.

Several Pakistani officials reached on Sunday declined to comment. The American assessments were disclosed Sunday by The Financial Times. The newspaper cited Pakistani officials who denied the accusations.

When pictures of the helicopter’s tail emerged in the days after the Bin Laden raid, defense experts said it bore little resemblance to a standard Black Hawk helicopter. They said that the helicopter in Abbottabad appeared to have a special coating designed to elude air defenses, and that the Black Hawk’s sharp edges seemed to have been replaced with curved parts that could further confuse ground radar systems.

Pakistan’s anger about the Bin Laden operation was so intense that officials in Islamabad, the capital, hinted in news reports in May that they might allow the Chinese to see the helicopter wreckage, but it was unclear at the time whether Pakistan’s government might follow through on the veiled threats. Pakistani officials also made a high-profile trip to Beijing shortly after the Abbottabad raid, part of a not-so-subtle campaign to show the strength of Pakistan’s alliance with China amid faltering relations between Washington and Islamabad.

Meanwhile, the intelligence services of the two countries have quietly carried out their own spy games. Pakistan’s military spy service, the Directorate for Inter-Services Intelligence, or ISI, arrested a group of Pakistani citizens in May who the agency suspected were working with the Central Intelligence Agency in the months leading up to the Bin Laden raid.

One of those arrested was a Pakistani doctor who had helped the C.I.A. set up a phony vaccination program in Abbottabad. The doctor had set up the vaccination scheme in the hope of gaining access to the Bin Laden compound and getting hard evidence that Bin Laden was hiding there. The doctor remains in Pakistani custody, according to American officials.

The C.I.A., for its part, has continued to carry out missile strikes inside Pakistan using armed drone aircraft, a campaign that has been tacitly blessed by Pakistani leaders but that has further aggravated relations between the C.I.A. and the ISI.

The relationship between the spy services began fraying in the months before the Bin Laden raid, after a C.I.A. contractor was charged with murder and jailed in Lahore. The contractor, Raymond A. Davis, killed two men at a crowded traffic stop in Lahore in January, in what American officials described as an act of self-defense after the two men tried to rob Mr. Davis.

Mr. Davis was eventually released from jail, but American relations with Pakistan declined steadily in subsequent weeks and sank even lower after the Bin Laden raid.

However, amid the recriminations and threats by members of Congress to cut all military aid to Pakistan, some senior members of the Obama administration have tried to dial back tensions before they do permanent damage to the shaky alliance.

Despite the headaches of an alliance marked by mutual distrust and competing agendas, the officials argue, the prospect of Washington permanently severing ties with a nuclear-armed country as volatile as Pakistan would be far more dangerous.