Seoul, South Korea ? North Korea said Saturday that it showed its “nuclear deterrent” to an unofficial U.S. delegation that visited the disputed Yongbyon nuclear complex, which had been closed to outsiders since the North expelled U.N. inspectors more than a year ago.

A member of the delegation, which included experts and former government officials, said the five Americans were allowed to see everything they requested, but it was not clear if the “nuclear deterrent” was a bomb. Delegates said they could give no further details until they reported to Washington.

The visit came amid efforts to arrange a new round of six-nation talks on ending the standoff over the North’s suspected nuclear weapons program, which Pyongyang says is necessary to defend the country against a possible U.S. invasion. A first round of talks in August ended without much progress.

“As everybody knows, the United States compelled the DPRK to build a nuclear deterrent,” North Korea’s official KCNA news agency quoted a Foreign Ministry spokesman as saying.

“We showed this to Lewis and his party this time,” the spokesman said, referring to one of the delegates, John W. Lewis, a Stanford University professor emeritus of international relations.

The delegates, who returned Saturday to Beijing, would not say how much time they spent at Yongbyon. Lewis said they met North Korean military, foreign affairs, scientific and economic officials but would not identify them or say what they discussed.

“We are a private delegation,” Lewis said. “We were not there to negotiate. We were not there to be inspectors.”

U.S. officials believe the North already has one or two nuclear bombs.