China is the North's only major ally.
"What's unimaginable to me is not a military option", Gen Dunford told reporters before a meeting with Chinese President Xi Jinping.
U.S. Chairman of the Joint Chiefs of Staff, Marine Corps Gen. Joseph Dunford, second from right, accompanied by U.S. Ambassador to China Terry Branstad, left, meets with China's State Counselor Yang Jiechi at the Zhongnanhai Leadership Compound in Beijing, China, on Thursday.
The top United States general on Tuesday said both the United States and China are committed to working through tough issues, which comes amid heightened tensions over North Korea's nuclear missile program, Reuters reported Tuesday.
Chief White House strategist Steve Bannon said on Wednesday there could be no military solution to the stand-off.
"The US might have told China [at the meeting] about their plan for a possible military response if North Korea attacks, because they would want to know how China would react", Li said.
"There's no military solution (to North Korea's nuclear threats), forget it", Bannon said in an interview with The American Prospect. "Until somebody solves the part of the equation that shows me that 10 million people in Seoul don't die in the first 30 minutes from conventional weapons, I don't know what you're talking about, there's no military solution here, they got us".
Earlier, Gen Dunford met with his Chinese counterpart Fang Fenghui, chief of the People's Liberation Army's joint staff department, another top general, Fan Changlong, and top foreign policy adviser Yang Jiechi.
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During Dunford's visit, the two militaries signed the framework to build a new communication mechanism for their joint staff departments, which Xi said will play a positive role in boosting bilateral ties.
"This is uncharacteristic of the normal safe behavior we see from the Chinese military", Pentagon spokesman Jeff Davis said after the incident.
The top US military officer told his Chinese counterpart yesterday that the USA and China have "many hard issues" to work through, during a visit that comes amid tensions over North Korea's missile program, Taiwan and China's claims in the South China Sea.
"The alternative would have been both catastrophic and unacceptable!"
The U.S. has expressed concerns about a lack of transparency in China military spending and what the United States calls unsafe intercepts of U.S. aircraft by the Chinese air force.
Gen Dunford told reporters that he has advised the USA leadership not to dial back on the exercises with South Korea.
"I know we share one thing: We share a commitment to work through these hard issues", he added, saying that with the guidance of political leaders "we are going to make some progress over the next few days".
Mr Trump tweeted that Kim had "made a very wise and well reasoned decision", referring to North Korean official media saying the leader would not give an immediate order to launch multiple missiles towards Guam.