The Bush administration claimed success on Tuesday for its program designed to intercept weapons technology, saying it helped end Libya's weapons program.

Secretary of State Condoleezza Rice said the Proliferation Security Initiative (search), an operation conducted jointly with dozens of other countries, provided the "framework" for intercepting centrifuge components bound for Libya and led to Moammar al-Qadhafi's 2003 decision to dismantle the programs.

The program has had 11 successful efforts, including the interception of missile and nuclear technology headed for Iran, Rice said at a State Department ceremony marking the program's second anniversary. She provided no additional details, but State Department spokesman Richard Boucher said two deliveries of equipment to North Korea (search) were intercepted and a second to Iran (search).

And President Bush, in a statement released by the White House press office, said many partners of the United States were developing new tools to improve their capacities to interdict weapons of mass destruction (search).

"We are working in common cause with like-minded states prepared to make maximum use of their laws and capabilities to deny rogue states, terrorists and black marketeers access" to weapons equipment, Bush's prepared statement said.

But Wade Boese, research director for the private Arms Control Association, challenged the claim the program was instrumental in blocking delivery to Libya.

"This is the only piece of evidence they have provided for the program's success, but it remains unclear what role PSI actually played in this interdiction," Boese said, using the program's initials. "Some former U.S. and foreign government officials have said that the interception was not a PSI operation."

Boese added: "We don't have any public accounting of interdictions except this one."

Boucher, the State Department spokesman, said other programs -- and not solely PSI -- played roles in the Libya interception. He didn't provide specifics, saying he did not want to jeopardize U.S. intelligence operations.

The United States and two allies, Singapore and Denmark, joined Tuesday in the anniversary event. More than 60 nations participate in the program.

John Negroponte (search), the U.S. national intelligence director, said "PSI makes intelligence actionable."

Along with terror, the spread of technology for weapons of mass destruction poses the greatest danger to nations around the world, Negroponte said.

Ambassador Heng Chee Chan of Singapore said her small city-state was grateful for the program as a bulwark against weapons proliferation and terrorism. Singapore is aggressively urging other Asian nations to join the program, she said.

And Ambassador Ulrik Andreas Federspiel of Denmark called the program "one of the most promising defenses against terrorism."

"We believe PSI is working," he said.

John R. Bolton (search), the undersecretary of state for arms control and international security, has championed and promoted the program from its inception, rallying countries to join and to engage in PSI exercises.

Bolton's nomination to be U.S. ambassador to the United Nations is under challenge in the Senate and he was not mentioned during the ceremony.