(CNN) -- North Korea threatened Tuesday to nullify the armistice agreement that ended the Korean War in 1953, citing U.S.-led international moves to impose new sanctions against it over its recent nuclear test, South Korea's Yonhap news agency reported.
The North's military said it will also cut off direct phone links with South Korea at the inter-Korean border village of Panmunjom, Yonhap said, citing North Korea's news outlet.
North and South Korea have technically been at war for decades. The 1950-53 civil war ended in a truce rather than a peace treaty.
A draft U.S. resolution to authorize more sanctions against North Korea in response to its controversial nuclear test was formally introduced Tuesday at the U.N. Security Council by U.S. Ambassador Susan Rice.
No vote on the draft resolution is expected Tuesday. A senior Obama administration official earlier told CNN that the United States and China, a key North Korean ally, had reached a tentative deal on the wording of the proposed resolution.
The two nations have been negotiating for weeks on the question.
Asked about sanctions, China's envoy Li Baodong said: "It depends on the council members."
There has been major concern in recent years among world powers over North Korea's nuclear aspirations.
Pyongyang continues to make "belligerent and reckless moves that threaten the region, their neighbors and now, directly, the United States of America," said U.S. Secretary of State John Kerry in a CNN interview on Tuesday.
"It's very easy for Kim Jong Un to prove his good intent here also. Just don't fire the next missile. Don't have the next test. Just say you're ready to talk," said Kerry, speaking on the last full day of his first international trip as the nation's top diplomat. Kim is North Korea's leader.
Addressing reporters later in Qatar, Kerry again put the onus on Kim to act, sayin,g "The American people and the world" would like to see him "take responsible actions" for peace.
"Rather than threaten to abrogate and threaten to move in some new direction, the world would be better served" if Kim took some action to engage in legitimate dialogue, Kerry said.
"Our preference is not to brandish threats to each other. It's to get to the table" to negotiate, he said.
As a permanent member of the Security Council with veto power, China can strongly influence the body's decisions and has previously resisted strong sanctions on the Kim regime, which it props up economically.
The two communist countries have been close allies since China supported the North with materiel and troops in the Korean War. The United States backed the South in the conflict, fighting side by side with its troops.
Analysts say Beijing wants to maintain the North as a buffer between its border and South Korea, a U.S. ally.
Beijing's government on Tuesday said it strives for a "nuclear free peninsula." It repeated its support for the U.N. Security Council's condemnation of North Korea's nuclear tests but also called for a muted response to it.
'Paying the price'
Mark Fitzpatrick, director of the Non-Proliferation and Disarmament Programme at the UK-based International Institute for Strategic Studies, told CNN that while the resolution will probably not be too onerous, the fact that China went along with another U.N. sanctions measure against North Korea reflects the growing anger and disillusionment that Beijing feels toward its supposed ally.
"Kim Jong Un is now paying the price for going ahead with a nuclear test despite Chinese warnings not to create trouble during the political transition that has been under way in Beijing the past year," Fitzpatrick said.
"The real question, though, is the degree to which China will be willing to implement the U.N. sanctions and to impose punishment of its own.
"A sharp drop in Chinese grain sales to North Korea in January may be a sign that China's support for U.N. sanctions is more than just a symbolic punishment."
Fitzpatrick characterized North Korea's reported threat to nullify the 1953 armistice as "largely bluster," pointing out that North Korea has "broken the armistice many times, most recently in 2010 by sinking a South Korean corvette and shelling a South Korean-populated island."
But, he added, "the threat does point to more trouble to come from the recalcitrant hermit kingdom. Things are going to get worse before they get better."
Pyongyang said the underground nuclear blast it conducted on February 12 was more powerful than its two previous detonations and used a smaller, lighter device, suggesting advances in its weapons program.
It was the first nuclear test the isolated state has carried out since its young leader inherited power in December 2011 after the death of his father, Kim Jong Il, who made building up North Korea's military strength the focus of his 17-year rule.
Like the regime's previous tests in 2006 and 2009, the move prompted widespread international condemnation, as well as a promise of tough action at the United Nations.
North Korea's government regularly rails against sanctions imposed on it.
The staging this week of joint U.S.-South Korean military exercises, known as Foal Eagle, has added to the simmering tensions, the official Korean Central News Agency reported Monday.
It described the training exercises as "an open declaration of a war" in the face of repeated warnings from the North that they should not be held.
The exercises have "touched off the pent-up resentment of the service personnel and people of (North Korea) and compelled them to harden their pledge to take thousand-fold retaliation against the enemies," the news agency said.
CNN's Elise Labott, Richard Roth, Anna Maja, Michael Pearson and Jethro Mullen contributed to this report.