Blaming the Democratic People's Republic of Korea (DPRK) of posing an "unusual and extraordinary threat" to U.S. security and foreign policy, President Barack Obama on Tuesday declared an extension of sanctions on DPRK for additional year.

In a letter to U.S. Congress, President Obama told lawmakers that he has decided to make the national emergency on DPRK, which will be expired on June 26, continue in effect for additional year. Under the national emergency, the administration could adopt a series of economic sanctions against Pyongyang.

"The existence and risk of the proliferation of weapons-usable fissile material on the Korean peninsula continue to pose an unusual and extraordinary threat to the national security and foreign policy of the United States," Obama explained, adding that it is necessary to maintain certain restrictions with respect to DPRK.

Apart from its sanctions, the administration has also voiced to enforce sanctions set in the 1874 UN Security Council Resolution, which condemns DPRK for its underground nuclear test May 25, 2009, that has obviously threatened the Asian-Pacific region's security and stability.

The resolution bans all weapons exports from the DPRK and most arms imports into the country, authorizes UN member states to inspect DPRK's sea, air and land cargo, and requires them to seize and destroy any goods transported in violation of the sanctions.

Last December, the United States and DPRK agreed on the need to resume negotiations during U.S. envoy's trip to Pyongyang. Washington has trying to persuade Pyongyang to return to the stalled six-party talks, while Pyongyang wants permanent peace and normalization with the United States before its denuclearization.

The United States, however, has dismissed a proposal by DPRK on negotiating a peace treaty, saying the first and foremost thing for Pyongyang must be to return the six-party talks.

Pyongyang quitted the six-party nuclear talks, which is also joined by the United States, China, South Korea, Japan and Russia, in April 2009 in anger over international criticism of its long-range rocket test.