The U.N. Security Council on Tuesday unanimously approved a resolution condemning North Korea's rocket launch in December and imposing new sanctions on Pyongyang's space agency.
The multi-stage rocket launch is considered part of a covert program to develop ballistic missiles that can carry nuclear warheads.
The council reiterated its previous demand that North Korea abandon its nuclear weapons program in a "complete, verifiable and irreversible manner" and cease launches.
China joined in approving the resolution, the first resolution in four years to expand the sanctions regime on North Korea.
"We believe that action taken by the Council should be prudent, measured, proportionate, and conducive to stability," Chinese Ambassador Li Baodong said after the vote.
China's agreement to join a resolution is a step away from the protection it usually gives to North Korea, its neighbour, which it supported in the Korean War in the early 1950s against U.S.-led U.N. troops.
China is seen as North Korea's closest ally, and its protection of North Korea meant that the Security Council previously denounced North Korea's launches with non-binding council statements, which are unenforceable.
In a defiant statement early Wednesday, North Korea's Foreign Ministry warned that it will strengthen its military and nuclear defences in reaction to what it called evidence of "U.S. hostility" toward Pyongyang. It also warned that it would rebuff any attempt to engage Pyongyang in disarmament negotiations.
"There can be talks for peace and stability of the Korean Peninsula and the region in the future, but no talks for the denuclearization of the peninsula," the Foreign Ministry said in a memorandum carried by the state-run Korean Central News Agency.
North Korea ominously warned that it would take steps to "bolster the military capabilities for self-defence, including the nuclear deterrence."
North Korea sent a satellite into space on Dec. 12 aboard a long-range rocket, a launch that the U.S. and its allies have criticized as a test of banned ballistic missile technology. Pyongyang maintains the launch was a peaceful bid to send a satellite into space and North Korean leader Kim Jong Un cited its success in his New Year's Day speech.
In 2006 and 2009, Pyongyang conducted atomic tests after being slapped with Security Council condemnation and sanctions for similar launches of long-range rockets.
Security Council resolutions ban North Korea from any use of ballistic missile technology, even if characterized as a satellite launch or space launch vehicle.
The resolution imposes new sanctions under existing authorities on North Korean companies and government agencies, including North Korea's space agency and several individuals.
It also updates lists of nuclear and ballistic missile technology banned for transfer to and from North Korea and includes several new provisions targeting North Korea's smuggling of sensitive items that could contribute to the prohibited programs.
In its talks with China, the U.S. had to agree that the resolution would not bring in new forms of sanctions but would build on the existing Security Council sanction regimes.
""We hope that all relevant sides can, with a view to maintaining peace and stability, stay calm and restrained, and avoid all acts that will escalate tension, which is conducive to the interest of all sides," Chinese Foreign Ministry spokesman Qin Gang said in Beijing on Wednesday. He stressed the importance of moving ahead with the six-nation, aid-for-disarmament talks.
China's support for the new resolution comes at a time when the region braces for the possibility that North Korea may test a nuclear device as it did following previous rocket launches. Satellite photos taken at North Korea's nuclear test site in Punggye-ri last month indicated continued activity, even in winter, according to analysis by 38 North, a North Korea website affiliated with the Johns Hopkins School for Advanced International Studies.
North Korea vowed last week to strengthen its defences amid concerns the country may conduct a nuclear test as a follow-up to last month's rocket launch.
Citing U.S. hostility, Pyongyang's Foreign Ministry said in a memorandum that North Korea will "continue to strengthen its deterrence against all forms of war."
The memorandum carried by state media did not say what action North Korea would take to defend itself. However, North Korea has claimed the right to build atomic weapons to protect itself from the United States, which stations more than 28,000 troops in South Korea.
