U.S. President Barack Obama said Thursday that the six-party talks will resume when there is evidence that North Korea is prepared to do so responsibly.

Obama said after a meeting with President Lee Myung-bak in Seoul that although both the U.S. and South Korea believe the multilateral talks will resume at some point, North Korea’s sincerity is a prerequisite.

Obama added that Seoul and Washington have continuously conveyed their stance on the nuclear issue to North Korea. He added that if the North shows no commitment to denuclearization and continues its provocative behavior, the reclusive state will remain isolated and underdeveloped.

Obama said that the international community is united in wanting the North to keep its word by choosing irrevocable dismantlement of its nuclear program. He said that if Pyongyang does so, all nations around the world would be willing to provide considerable amounts of aid and assistance to North Korea.