The U.S. government said on Tuesday that the Democratic People's Republic of Korea (DPRK) would violate its international obligation if it restarts operations at the Nyongbyon nuclear complex.

"The fact is that North Korea's announcement that it will reopen or restart its nuclear facilities at Nyongbyon is another indication of its pattern of contradicting its own commitments and its pattern of violating its international obligations," said White House spokesman Jay Carney at a briefing.

"As you know, that facility has been dormant as part of an agreement, which North Korea, at least with this announcement, seems to be willing to violate," he told reporters.

On the same day, State Department spokeswoman Victoria Nuland also told reporters at a regular briefing that such a move would be a "clear violation" of Pyongyang's international obligations.

While noting there is a "long way" to go between a stated intention and actually restarting the operations, Nuland pointed out that it would be "extremely alarming" if Pyongyang does reopen its Nyongbyon nuclear facility.

The DPRK said Tuesday it has decided to restart operations at the Nyongbyon nuclear complex.

A spokesman for DPRK's General Department of Atomic Energy told the official KCNA news agency that the country will "readjust" and "restart" all nuclear facilities at the complex, including a uranium enrichment plant and a 5MW graphite moderated reactor that had been "mothballed and disabled under an agreement reached at the six-party talks in October, 2007."

Such a move came days after the DPRK claimed that it had entered a "state of war" with South Korea.

Tensions have been running high on the Korean Peninsula since the DPRK conducted its third nuclear test on Feb. 12 as a countermeasure against the joint military drills of the United States and South Korea.

The DPRK has also threatened to launch a preemptive nuclear strike for self-defense and unilaterally nullified the 1953 armistice that suspended the Korean War.

The U.S. Navy was moving a sea-based radar platform closer to the Korean Peninsula in order to monitor military moves of the DPRK, including possible new missile launches, CNN quoted a Pentagon official as saying on Monday.