While Gates did not directly confirm the reports, his comments were the first public acknowledgment by U.S. officials of the Pakistan arrests — the latest flare-up between the U.S. and Islamabad since the May 2 operation that took U.S. troops deep into the country to get bin Laden.
Reflecting the growing impatience in Congress with the war in Afghanistan and the sometimes tepid support from Pakistan, Democratic Sen. Patrick Leahy of Vermont grilled Gates during a Capitol Hill hearing, demanding: "How long do we support governments that lie to us? When do we say enough is enough?"
Gates responded that based on his 27 years at the CIA and more than four as Pentagon chief, "most governments lie to each other. That's the way business gets done."
"Do they also arrest the people that help us, when they say they're allies?" Leahy pressed.
"Sometimes," replied Gates, adding, "and sometimes they send people to spy on us, and they're our close allies. That's the real world that we deal with. "
The sharp exchange came during an otherwise friendly Senate defense appropriations subcommittee hearing, where members lauded Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, for their service during difficult times of war.
Mullen told senators that the U.S. is struggling to rebuild its badly broken relationship with Pakistan. But the arrests have driven another wedge between the two countries, angering Congress, which controls the purse strings for the billions of dollars in aid Islamabad receives.
A Western official in Pakistan has confirmed that five Pakistanis were arrested by Pakistan's top intelligence service.
The group of detained Pakistanis included the owner of a safe house rented to the CIA to observe bin Laden's compound in Abbottabad, an army town not far from the Pakistani capital of Islamabad, a U.S. official said. The owner was detained along with a "handful" of other Pakistanis, said the official.
The Western officials spoke on condition of anonymity to discuss sensitive intelligence matters.