North Korea has announced that it is cancelling a hotline and a nonaggression pact with South Korea while reiterated past threats in anger over a UN Security Council vote to impose more sanctions on the country for its third nuclear test.
A statement the North issued on Friday said the country would retaliate with "crushing strikes" if enemies intruded into its territory.
It also said that North Korea was voiding past inter-Korean nuclear disarmament statements.
North Korea previously said it was cancelling a hotline with the US and the armistice that closed the Korean War in 1953.
Thursday's Security Council resolution will tighten financial restrictions on North Korea and crack down on its attempts to ship and receive banned cargo in breach of UN sanctions.
The US-drafted statement, which was approved unanimously by the 15-nation council, was the product of three weeks of negotiations between the US and China after North Korea's February 12 nuclear test.
Ban Ki-moon, the UN secretary-general who is a former South Korean foreign minister, welcomed the council's move, saying in a statement that the resolution "sent an unequivocal message to [North Korea] that the international community will not tolerate its pursuit of nuclear weapons".
Cash transfers targeted
Al Jazeera's diplomatic editor, James Bays, reporting from the UN headquarters in New York, said the resolution was "pretty much a certainty".
The resolution is targeting North Korean diplomats, cash transfers and access to luxury goods.
"I think it is fair to say that this resolution does expand the sanctions regime - not really looking at any new areas to sanction ... the North Korean economy, but what it is trying to do is close the loop holes," our diplomatic editor said.
It imposes asset freezes and travel bans on three individuals and two firms linked to North Korea's military.
|Spotlight coverage of tension in Northeast Asia
The UN vote came just hours after North Korea threatened to use its right to a pre-emptive nuclear attack against its aggressors.
North Korea has accused the US of using military drills in South Korea as a launch pad for a nuclear war and has scrapped the armistice with Washington that ended hostilities in the 1950-53 Korean War.
"Now that the US is set to light a fuse for a nuclear war, revolutionary armed forces... will exercise the right to a pre-emptive nuclear attack to destroy the strongholds of the aggressors," a foreign ministry spokesman said in a statement carried by the Korean Central News Agency (KCNA).
The US said on Thursday it was "fully capable" of defending itself against any North Korean ballistic missile strike.
Jay Carney, White House spokesman, said the US military could deal with any such attack and repeated earlier warnings that North Korea would gain nothing by threats and provocations.
Third nuclear test
The North conducted its third nuclear test in defiance of UN resolutions, and declared it had achieved progress in securing a functioning atomic arsenal.
Although North Korea boasts of nuclear bombs and pre-emptive strikes, it is not thought to have mastered the ability to produce a warhead small enough to put on a missile capable of reaching the US mainland.
It is believed to have enough nuclear fuel, however, for a handful of crude nuclear devices.
|The latest UN resolution targets North Korean diplomats, cash transfers and access to luxury goods [AFP]
The North's unnamed foreign ministry spokesman also said it would be entitled to take military action as of March 11 when US-South Korea military drills move into a full-scale phase as it had declared the truce invalid.
It is the latest in an escalation of tough words from both sides of the armed Korean border this week as the UN Security Council deliberates a resolution to tighten financial sanctions and a naval blockade against the North.
North Korea, which held a mass military rally in Pyongyang on Thursday in support of its recent threats, has protested against the UN censures of its rocket launches.
It says they are part of a peaceful space programme and that the criticism is an exercise of double standards by the US.
In 2010, the North bombed South Korea's Yeonpyeong Island killing two civilians. It is widely accused of sinking a South Korean navy ship earlier in the year, killing 46 sailors.
North Korea was conducting a series of military drills and getting ready for state-wide war practice of an unusual scale, South Korea's defence ministry said earlier on Thursday.
South Korea and the US, which are conducting annual military drills until the end of April, are watching the North's activities for signs they turn from an exercise to an actual attack, a South Korean official said.