A Chinese state-run newspaper called on Beijing on Friday to "stay neutral" if North Korea strikes first in a conflict with the United States, despite a mutual defence pact between the Asian allies.
The nationalistic Global Times tabloid said in an editorial that Washington and Pyongyang were playing a "reckless game" that could lead to "miscalculations and a strategic 'war'".
"Beijing is not able to persuade Washington or Pyongyang to back down at this time," the Global Times said.
"It needs to make clear its stance to all sides and make them understand that when their actions jeopardize China's interests, China will respond with a firm hand."
The commentary came after Washington warned North Korea this week it faced "fire and fury like the world has never seen" if it continued to threaten the US with its missile and nuclear programmes.
That prompted a defiant Pyongyang to threaten a missile attack on Guam, a tiny US territory in the Pacific that is home to major US air and naval facilities.
China -- which has been accused by the US of not doing enough to rein in its longtime ally -- has maintained that political dialogue is the only solution.
China fought alongside the North in the 1950-53 Korean War and the two nations signed a mutual defence pact in 1961, but the Global Times suggested Beijing should remain on the sidelines if Pyongyang launches the first salvo in a new conflict with the United States.
"China should also make clear that if North Korea launches missiles that threaten US soil first and the US retaliates, China will stay neutral," the editorial said.
"If the US and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so."