North Korea should first refrain from provocative acts and abide by international obligations before demanding the dismantlement of the United Nations Command (UNC) and the signing of a peace treaty on the peninsula, a U.S. government official said Monday.

"The United States has made clear that we are prepared to engage constructively with North Korea if it chooses to live up to its own commitments, fulfill its international obligations, deal peacefully with its neighbors, and refrain from acts that threaten regional and international peace and stability," the official told Yonhap News Agency on the condition of anonymity.

The official said Washington wants Pyongyang to stop violating U.N. resolutions, citing the communist nation's latest long-range rocket launch in December.

The official dismissed speculation that the U.N. response to the launch is tapering off due to China's uncooperative attitude and more urgent global issues such as Mali and Syria.

"We are working closely with six-party talks partners, United Nations Security Council member states, and other countries on a clear and credible response" to the launch, the official said.

The official was responding to a "memorandum" issued by the North's foreign ministry on Monday (Seoul time).

The ministry demanded the UNC be scrapped as the two Koreas this year mark the 60th anniversary of the armistice that ended the 1950-53 Korean War.

The UNC is the unified command structure for the U.S.-led multinational forces that supported South Korea in its fight against the invading North in the war.

The UNC, headed by the commander of U.S. Forces Korea, still exists as the two Koreas are locked in a fragile state of ceasefire.

Pyongyang labeled the UNC as a "tool of war which was organized by the U.S. for the purpose of deploying its satellite forces and exercising its control over them during the Korean War."

The communist regime called for replacing the armistice with a peace treaty and insisted removing the UNC is a prerequisite.

"Whether the U.S. immediately dismantles the 'UN Command' or not will serve as the acid stone in deciding whether the U.S. will maintain or not its anti-DPRK (North Korea) hostile policy, whether it wants peace and stability or the revival of the Cold War in the Asia-Pacific region," the ministry said in the English-version memorandum.

It added the North will continue to strengthen its deterrence against all forms of war. (Yonhap News)