NEW YORK - North Korea's deputy U.N. ambassador warned Monday that the situation on the Korean peninsula "has reached the touch-and-go point and a nuclear war may break out any moment."

Kim In Ryong told the U.N. General Assembly's disarmament committee North Korea is the only country in the world that's been subjected to "such an extreme and direct nuclear threat" from the United States since the 1970s -- and said his country has the right to possess nuclear weapons in self-defense.

He pointed to large-scale military exercises every year using "nuclear assets" and said what is more dangerous is what he called a U.S. plan to stage a "secret operation aimed at the removal of our supreme leadership."

This year, Kim said, North Korea completed its "state nuclear force and thus became the full-fledged nuclear power which possesses the delivery means of various ranges, including the atomic bomb, H-bomb and intercontinental ballistic rockets."

"The entire U.S. mainland is within our firing range, and if the U.S. dares to invade our sacred territory even an inch, it will not escape our severe punishment in any part of the globe," he warned.

Kim's speech follows escalating threats between North Korea and the United States, and increasingly tough U.N. sanctions.

It also stunned diplomats, reports CBS News' Pamela Falk.

Russian President Vladimir Putin said Monday that his country is curtailing economic, scientific and other ties with Pypongyang in line with U.N. sanctions, and the European Union announced new sanctions on Pyongyang for developing nuclear weapons and ballistic missiles.

North Korea's deputy U.N. ambassador called his country's nuclear and missile arsenal "a precious strategic asset that cannot be reversed or bartered for anything."

"Unless the hostile policy and the nuclear threat of the U.S. is thoroughly eradicated, we will never put our nuclear weapons and ballistic rockets on the negotiating table under any circumstances," Kim said.

He told the disarmament committee the Democratic People's Republic of Korea - North Korea's official name - had hoped for a nuclear-free world.

The Associated Press contributed to this report.