WASHINGTON (Yonhap) -- A U.S. diplomat handling Korea affairs said Wednesday that Washington is willing to "constructively engage" with Pyongyang if it ceases provocation.

Jim Zumwalt, deputy assistant secretary of state for East Asian and Pacific affairs, stressed that the U.S. is not interested in talks for the sake of talks.

"The United States is prepared to engage constructively with North Korea, but its new leadership must understand that there will be no rewards for provocations," he said at a congressional hearing.

He was defending the Obama administration's policy on the recalcitrant nation against criticism from mostly Republican members of the House Subcommittee on Asia and the Pacific, led by Rep. Donald Manzullo (R-IL).

He urged North Korea to choose a different approach. The communist nation fired a long-range rocket in April, virtually terminating a Feb. 29 agreement with Washington.

The deal called for Pyongyang to suspend some of its nuclear activities and impose a moratorium on ballistic missile launches and nuclear testing.

Multiple reports, based on satellite images, say that the North seems to be preparing for its third nuclear experiment.

Zumwalt said the U.S. is "very frustrated" with the lack of progress in talking with North Korea.

But the U.S. remains "determined and prepared" to resume a dialogue if the nation changes its attitude.

He also reiterated the administration's concern for the well-being of the North Korean people.

"We remain deeply concerned about the dire human rights situation in North Korea," he said.