Donald Trump's national security advisor, HR McMaster, has warned that the chances of a military conflict with North Korea are "increasing every day."
The rogue nation is "the greatest immediate threat to the United States," he told a US national defence conference in California on Saturday (2 December).
On the subject of a potential war, he said: "I think it's increasing every day, which means that we are in a race, really, we are in a race to be able to solve this problem."
He comments came after the North Korean regime conducted another ballistic missile test.
The top defence chief called on China to help enforce sanctions on Pyongyang, saying that a denuclearised Korean peninsula was "in China's interest."
He asked Beijing to slash oil imports to its troublesome - but allied - neighbouring country. He noted: "You can't shoot a missile without fuel."
McMaster said the outbreak of war was a last resort, but indicated the US is running out of options, saying "there are ways to address this problem short of armed conflict, but it is a race because [leader Kim Jong-un is] getting closer and closer, and there's not much time left."
He continued: "We're asking China to act in China's interest, as they should, and we believe increasingly that it's in China's urgent interest to do more."
Following the latest missile test on 28 November (Tuesday), China's Foreign Ministry voiced "grave concern and opposition" directed toward the North Korean leader.
But one Chinese state media outlet published an editorial indicating that it, at least in part, blamed the American government for the sharp rise in tension with the North.
The Global Times ran an editorial on 1 December lashing out at the stance of the Trump administration, saying: "The theory that China should be held responsible is wrong in logic."
It continued: "When tensions on the Korean Peninsula reach a new height, a large portion of the pressure is transferred to China. But the US and North Korea must shoulder their own responsibility without making China the scapegoat."
Since taking office, Trump has launched a series of Twitter attacks on Jong-un, branding him "little rocketman." The leader has hit back, calling the president an "old lunatic" and "human reject."
On Tuesday, North Korea launched a Hwasong-15 intercontinental ballistic missile (ICBM) - in violation of international political sanctions. South Korea's military officials said that the missile - which is potentially capable of hitting Washington DC - landed in the sea near Japan.
The missile was in the air for 50 minutes and travelled about 1,000km (650 miles).
Images and videos released by a state-run broadcaster following the missile's launch showed fireworks and dancing on the streets of the nation's capital city, Pyongyang.