North Korea's top diplomat is saying that "under no circumstances" will it put its nuclear weapons or ballistic missiles on the negotiating table, after Secretary of State Rex Tillerson said that the U.S. was open to talks if the North completely halts its nuclear program and stops conducting intercontinental ballistic missiles (ICBM) tests.

North Korean Foreign Minister Ri Yong Ho also stated at a meeting of the Association of Southeast Asian Nations that his country has no intention of using nuclear weapons against any country "except the U.S." He says the only way that would change is if another country joined in an American action against North Korea.

Ri had been scheduled to hold a news conference in Manila, Philippines, where Asian diplomats are attending the ministerial meetings. Instead, Ri's spokesman handed reporters a copy of a speech that Ri had given at the meeting.

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Ri says in the speech that responsibility for the Korean Peninsula crisis lies solely with Washington. He says the North is "ready to teach the U.S. a severe lesson with its nuclear strategic force."

Over the weekend, the U.N. Security Council unanimously approved new sanctions to punish the North including a ban on coal and other exports worth over $1 billion. U.S. Ambassador Nikki Haley called the U.S.-drafted resolution "the single largest economic sanctions package ever leveled against" North Korea.

A statement from the North Korean government on Monday said that the U.N. sanctions resolution "is an outcome of diabolical attempts of the U.S. to isolate and stifle" the North, and it called the resolution an infringement on the regime's sovereignty.

The regime claimed its pursuit of nuclear force is a self-defense measure against "the high-handed and arbitrary acts of the U.S.," which it accused of pursuing policies of "extreme hostility" and which poses a nuclear threat against North Korea.

The North said it would take an unspecified "resolute action of justice" and would never place its nuclear program on the negotiating table or "flinch an inch" from its push to strengthen its nuclear deterrence as long as U.S. hostility against North Korea persists.

North Korea also mocked the U.S. for being "so frightened" by the ICBM tests and said the North's neighbors and the U.S. are "making such a scene baying at each other" over the missile launches. It went on to say that it's "only a forlorn hope" that North Korea would change its stance because of the sanctions. In the statement, North Korea also threatened to "make the U.S. pay dearly for all the heinous crime [SIC] it commits against the state and people of this country."

South Korea's government said the North would face stronger sanctions if it doesn't stop its nuclear and missile provocation.

Lim Eul Chul, a North Korea expert at South Korea's Kyungnam University, said the comments by the North demonstrate how angry it is over the U.N. sanctions, but the country is not likely to launch a pre-emptive strike against the United States. He said the North could still carry out further missile tests or a sixth atomic bomb test in the coming months under its broader weapons development timetable.

North Korea test-launched two ICBMs last month as part of its efforts to possess a long-range missile capable of striking anywhere in the mainland U.S. Both missiles were fired at highly lofted angles, and analysts say the weapons could reach parts of the United States such as Alaska, Los Angeles or Chicago if fired at a normal, flattened trajectory.

The centerpiece of the U.N. sanctions is a ban on North Korean exports of coal, iron, lead and seafood products - and a ban on all countries importing those products, estimated to be worth over $1 billion a year in hard currency. The resolution also bans countries from giving any additional permits to North Korean laborers, another source of foreign currency for the North, and prohibits all new joint ventures with North Korean companies.

Analysts say that North Korea, already under numerous U.N. and other international sanctions, will feel some pain from the new sanctions but is not likely to return to disarmament negotiations anytime soon because of them.

Lim, the North Korea expert, said the North will probably squeeze its ordinary citizens to help finance its nuclear and missile programs. Shin Beomchul of the Seoul-based Korea National Diplomatic Academy said sanctions that can force a change from North Korea would include a ban on China's annual, mostly free shipment of 500,000 tons of crude oil to North Korea and the deporting by U.N. member states of the tens of thousands of North Korean workers currently dispatched abroad.

CBS News' Pam Falk contributed to this report.