North Korea appears bent on holding on to its nuclear weapons no matter what happens, but concerted international sanctions and pressure can lead to the communist regime rethinking its nuclear calculus, a top South Korean diplomat said Monday.

"Pyongyang's behavior often seems unpredictable, like that of a poker player. Pyongyang does not look likely to give up nuclear weapons no matter what happens. However, it does respond to external stimuli," Deputy Foreign Minister Kim Hyoung-zhin said at a seminar in Washington.

"When the international community displayed a firm and united attitude, North Korea made gestures for compromise," he said, adding that a sincere change in Pyongyang's attitude can be achieved through "the full implementation of the U.N. resolutions, bilateral sanctions by major countries and international pressure against the North.

"If these elements are tightly interwoven without any loophole like the weft and warp over fabric, the Kim Jong-un regime will realize it cannot survive unless it gives up its nuclear program and take steps toward denuclearization," the diplomat said.

Kim said that President Park Geun-hye and U.S. President Barack Obama have agreed to address the North Korean nuclear problem with utmost urgency and determination, and the two countries have been taking various actions to "show North Korea these commitments are not just empty words."

Following the North's fourth nuclear test, the U.S. sent its B-52 strategic bomber over South Korea in a show of its commitment to Seoul's defense, and the two allies have also carried out annual joint military exercises on a larger scale than before, Kim said.

Seoul and Washington have also launched discussions on deploying the THAAD missile defense system to the South to "respond more effectively to North Korea's threats, which have gone through qualitative changes," Kim said.

Kim said the Korea-U.S. alliance is key to regional peace and prosperity, along with trilateral cooperation between Seoul, Washington and Tokyo. In addition, establishing a trilateral dialogue channel among South Korea, the U.S. and China can create new momentum in resolving tricky regional issues, he said.

"Korea and the United States should play a more active role in facilitating multilateral cooperation among all the counties in the region," Kim said.

Kim also said that Seoul has been working hard to make Park's vision for regional peace, known as the Northeast Asia Peace and Cooperation Initiative, take root as a new process for multilateral cooperation.

"This initiative can generate a synergy effect with the U.S. rebalancing strategy and help the Korea-U.S. alliance become a strategic alliance in the true sense of the word," he said.

Kim said he firmly believes that the Korea-U.S. will "continue to demonstrate true partnership with fair sharing of burden" and establish itself as the linchpin of peace and stability on the Korean Peninsula, in Northeast Asia and beyond.

By "fair sharing of burden," Kim was believed to have rejected U.S. Republican presidential front-runner Donald Trump's baseless claims that South Korea has been getting a defense free ride from the U.S. without paying a fair share of the costs necessary for the upkeep of some 28,500 American troops stationed in the South.

Monday's CSIS seminar came amid growing concern that North Korea could carry out yet another nuclear test soon.

"Will they do a fifth test? Of course. Will they do another missile test? Of course. We just don't know the timing," Bruce Klinger, a senior Korea expert at the Heritage Foundation, said during the seminar.

In separate comments send to Yonhap News Agency, Klinger said that a nuclear test is "only a matter of time."

"Pyongyang will continue to conduct tests in order to refine, improve, and demonstrate its nuclear weapons capability. Given the observed activity, a nuclear test could occur at any time," he said. "Kim Jong-un seems desperate to prove his nuclear and missile prowess." (Yonhap)