The US and China are working on a "range of options" following North Korea's latest missile test, the top security adviser to US President Donald Trump says.
Lt Gen HR McMaster told ABC News that there was consensus with China that the situation "could not continue".
His comments come after a failed missile test launch by North Korea and a massive military parade.
President Trump had earlier said China was "working with us" on the issue.
Beijing, Pyongyang's biggest ally, has come under pressure from Washington to exert more pressure on its neighbour.
Sunday's comments appear to be the first confirmation that both countries are working together on how to deal with the North Korean issue.
Mr McMaster, who was in the Afghan capital, Kabul, said the latest launch "fits a pattern of provocative and destabilising and threatening behaviour".
"The president has made clear that he will not accept the United States and its allies and partners in the region being under threat from this hostile regime with nuclear weapons," he said.
"I think there's an international consensus now, including the Chinese and the Chinese leadership, that this is a situation that just can't continue."
Earlier on Sunday, South Korean and US military officials said a North Korean missile had detonated soon after launch.
The US Pacific Command said it believed it to be a ballistic missile.
Investigations were continuing, but one unnamed US official said it was unlikely to have been an intercontinental (ICBM) missile.
Ballistic missiles follow high trajectories and are initially powered and guided, but fall to their target under gravity.
Meanwhile, US Vice-President Mike Pence is on a 10-day tour of Asia intended to reassure allies of US commitment to their security.
In the South Korean capital, Seoul, Mr Pence called the failed launch a "provocation".
He is set to discuss North Korea with acting President Hwang Kyo-ahn.