After the latest missile test by North Korea at the end of last month, the USA intensified its pressure on Beijing.
Tension has been rising over North Korea's nuclear and missile programmes, which it pursues in defiance of years of U.N. Security Council resolutions, with bellicose rhetoric coming from both Pyongyang and the White House.
The UN Security Council unanimously imposed new sanctions on North Korea last Friday for its recent intercontinental ballistic missile test.
The UN resolution seeks to ban almost 90 per cent of refined petroleum exports to North Korea by capping them at 500,000 barrels a year and, in a last-minute change, demands the repatriation of North Koreans working overseas within 24 months, instead of 12 months as first proposed.
"We define this "sanctions resolution" rigged up by the USA and its followers as a grave infringement upon the sovereignty of our Republic, as an act of war violating peace and stability in the Korean peninsula and the region and categorically reject the 'resolution.' North Korea 's foreign ministry also said in a statement that the sanctions are tantamount to a "complete economic blockade" of North Korea".
China, which accounts for about 90 percent of the North's trade and is a main supplier of oil to the country, also insisted on diplomacy.
The United States and China will jointly monitor the implementation of sanctions on North Korea, Japanese daily Asahi Shimbun reported, citing us officials.
At the same time, the North is also likely to attempt to engage with South Korea in order to restore inter-Korean relations next year, it also said. Citing unnamed sources, the daily said there was a dramatic step-up in preparations for a military response to North Korea's missile tests.
"China has made enormous efforts to push for settlement through dialogue and negotiations and has paid a price higher than all the other parties for the goal of implementing the council's resolutions", Deputy Ambassador Wu Haitao said. There was no immediate reaction from the White House or North Korea to the South Korean prediction.
North Korea has said it is a "pipe dream" for the United States to think it will give up its nuclear weapons.
Tensions have been rising over North Korea's nuclear and missile programmes, which years of United Nations resolutions have failed to deter the regime from pursuing.
In addition, the resolution subjects the Ministry of the People's Armed Forces and 16 more North Korean individuals to a global asset freeze and travel ban.