"As long as U.S. nuclear aircraft carriers sail in the seas around our country, our nuclear deterrent can never be abandoned, but should be strengthened further," North Korean Deputy Foreign Minister Pak Kil-yon told the UN General Assembly.

"This is the lesson we have drawn," he said.

Relations between North and South Koreas dropped to a new low in March when a South Korean naval ship, the Cheonan, sunk near the disputed Northern Limit Line in the Yellow Sea causing the loss of 46 lives. An international investigation said the North was to blame, but the reclusive regime denied involvement.

Pak said Pyongyang considers naval exercises held by the United States and South Korea off the Korean Peninsula a serious threat. Antisubmarine exercises are currently underway in the area.

He said that without his country's nuclear deterrent, the Korean Peninsula "would have been turned into a battlefield scores of times, thus destroying regional peace and security."

North and South Korea remain technically at war, since no peace treaty was signed following the Korean War in 1953. The Demilitarized Zone between the countries is the most heavily armed border in the world.

Pak said, however, that Pyongyang does not intend to attack anyone.

"Our nuclear weapons are not a means to attack or threaten others, but a self-defensive deterrent ... to counter aggression and attack from outside," he said.