WASHINGTON: Defense Secretary Robert Gates says in an Associated Press interview that the Obama administration was disappointed by the unexplained failure of a US effort to share intelligence with Pakistan on the location of militants' suspected bomb facilities.

As an act of faith to restore relations with Pakistan, US intelligence in recent weeks shared the location of two such compounds in Pakistan's tribal areas. But by the time authorities reached the facilities, they had been vacated, Gates said.

The soon-to-retire Pentagon chief said he was not certain how or why the effort went awry. He said “'there was clearly disappointment on our part.” Others have raised the possibility that Pakistan's intelligence service had tipped off the militants.