N. Korea talks tough on uranium

SEOUL, South Korea — North Korea said Friday it is on the threshold of mastering a new way of building atomic bombs, pressuring the United States to agree to direct negotiations or see the communist regime become a greater nuclear risk.

Pyongyang's claim to have succeeded in experimental uranium enrichment — an easier way to make nuclear weapons — raises concerns that North Korea may add uranium-based weapons to enlarge its stockpile of atomic bombs made from plutonium.

North Korea also said it is continuing to weaponize plutonium.

The tough talk came as Washington showed no signs of easing pressure on North Korea, despite its recent series of conciliatory gestures, including releasing two detained American journalists and reportedly inviting top U.S. envoys to Pyongyang.

"We are prepared for both dialogue and sanctions," the North said in a letter to the U.N. Security Council carried Friday by its official Korean Central News Agency. If some veto-wielding permanent members of the council put "sanctions first before dialogue, we would respond with bolstering our nuclear deterrence first before we meet them in a dialogue," it said.

The Security Council slapped tough sanctions on North Korea for conducting an underground nuclear test in May.

The North said it does not oppose the denuclearization of the Korean peninsula, but warned it would be left with no choice but to take "yet another strong self-defensive countermeasure" if the standoff continues. It did not elaborate on possible countermeasures.

The letter stressed "the denuclearization of the Korean peninsula is closely related with the U.S. nuclear policy towards the DPRK." Those are the initials for the Democratic People's Republic of Korea, the country's official name.

The letter was sent to U.S. Ambassador Susan Rice, this month's president of the Security Council. The U.S. mission said it was received Thursday and sent to the 14 other council members that night.

U.S. State Department spokesman Ian Kelly said the North's announcement was troubling.

"We are very concerned by these claims that they are moving closer to the weaponization of nuclear materials, but I can't really comment on the veracity, how true these claims are," Kelly said.

Security Council diplomats said they do not anticipate a council meeting on the letter or a new U.N. resolution.