"We hope all relevant parties can maintain calm and restraint and take steps to alleviate tensions and not provoke each other", Chinese Foreign Ministry spokesman Geng Shuang said in a statement.
The unnamed Foreign Ministry spokesman said: 'The large-scale nuclear war exercises conducted by the United States in succession are creating touch-and-go situation on the Korean peninsula and series of violent war remarks coming from the USA high-level politicians amid such circumstances have made an outbreak of war on the Korean peninsula an established fact.
North Korea's state media confirmed the arrival of Mr Feltman and his entourage late on Tuesday without offering more details, later issuing a photograph of him and two members of his team.
On Thursday, North Korea asked a startling question: "When will the war break out?"
US Republican Senator Lindsey Graham urged the Pentagon on Sunday to start moving US military dependants out of South Korea, saying conflict with North Korea was getting close. North Korea's increasing nuclear and missile capability would top the agenda, it said.
He said: "We do not wish for a war but shall not hide from it". The Pentagon has mounted repeated shows of force after North Korean tests. Their exercise was simulated to target key North Korean facilities including nuclear and missile sites.
The flights by the B-1B, one of the US' largest strike aircraft, have played a leading role in Washington's attempts to increase pressure on North Korea to abandon its weapons programmes.
The weekend saw both White House national security adviser H.R. McMaster and U.S. Senator Lindsey Graham of SC say chances of war with Pyongyang were growing.
On Wednesday, the U.S. ambassador to the United Nations, Nikki Haley, raised doubts about USA participation in the Olympic Winter Games in South Korea in February, telling Fox News that Washington was concerned about its citizens.
As tensions soar, such drills are increasingly provocative, but also increasingly risky, with the ever-present threat that North Korea will interpret a drill as a real attack and retaliate, starting a full-scale war.
And though the United States has its top-of-the-line jets in South Korea for the exercise, it could still ratchet up pressure more - for example, Sun said, by engaging in covert, unattributable military actions against North Korea's nuclear infrastructure or stepping up cyberattacks.