US Secretary of State Rex Tillerson has offered reassurances to North Korea that the US does not seek regime change, and wants to have a dialogue.
But he emphasised that the US is still relying on China to pressure North Korea - a tactic many analysts say will not work. Implementing secondary sanctions on Chinese entities that do business with North Korea could also cloud broader trade negotiations with Beijing, they say.
But the United States has few options. US credibility is also at stake, a diplomat based in Washington told The Straits Times on condition of anonymity. "If North Korea is normalised as a nuclear power, there are other countries like Iran that will notice," the diplomat said.
There is a new sense of urgency following North Korea's successful test of an intercontinental ballistic missile (ICBM) last week - the second in a month - which experts say could reach deep into the US mainland.
The dilemma has the US sending mixed signals, alternately bellicose and conciliatory. The Trump administration has been "incoherent, and not just on North Korea", said North Korea expert Sue Mi Terry at the Bower Group Asia consultancy.
"But North Korea's latest ICBM tests shifted the bar. Secondary sanctions will absolutely strain the US-China relationship, but however productive or unproductive they may be, they are the only thing the US has," she told The Straits Times.
On the eve of a trip to South-east Asia to attend the Asean Regional Forum in Manila, Mr Tillerson struck a conciliatory note.
"We do not seek the collapse of the regime. We do not seek an accelerated reunification of the peninsula. We do not seek an excuse to send our military north of the 38th parallel," he told reporters on Tuesday in Washington. "We are trying to convey to the North Koreans we are not your enemy, we are not your threat, but you are presenting an unacceptable threat to us, and we have to respond."
He added: "We hope that at some point, they will begin to understand that, and that we would like to sit and have a dialogue with them."
Analysts say that will cut little ice at present as the US wants Pyongyang to give up its nuclear weapons programme, which the regime says is non-negotiable.
A war with North Korea would be catastrophic. Given that, the US continues to bank on China. "Our other options, obviously, are not particularly attractive," Mr Tillerson said.
China accounts for 90 per cent of economic activity with North Korea.
"China has ways that they can put pressure on and influence the North Korean regime because of this significant economic relationship that no one else has," Mr Tillerson said. "They do not see it in their interest for North Korea to have nuclear weapons, just as we do not see it in anyone's interest."
But analysts are sceptical that the strategy will work, saying that while it is in Beijing's interest to contain the Pyongyang regime, it is unrealistic for China not to have any business relationship with North Korea.
Another potential problem for the strategy is that the increasing chill in US-Russia relations could throw a lifeline to the Pyongyang regime even if China closes the tap.
Last Friday, following North Korea's test of an ICBM, Mr Tillerson said: "As the principal economic enablers of North Korea's nuclear weapon and ballistic missile development programme, China and Russia bear unique and special responsibility for this growing threat to regional and global stability."
That drew a sharp reaction from Moscow. On Monday, Russia's Foreign Ministry said: "We view as groundless attempts undertaken by the US and a number of other countries to shift responsibility to Russia and China, almost blaming Moscow and Beijing for indulging the missile and nuclear ambitions of (Pyongyang)."
China's Ambassador to the United Nations, Mr Liu Jieyi, said: "No matter how capable China is, China's efforts will not yield practical results because it depends on the two principal parties (the US and North Korea)."
On Tuesday, Mr Tillerson appeared to try to clarify the US stance, saying: "We have been very clear with the Chinese; we certainly don't blame the Chinese for the situation in North Korea. Only the North Koreans are to blame for this situation."
President Donald Trump yesterday signed a Bill that imposed tougher sanctions on North Korea and Iran for their missile programmes as well as on Russia for alleged meddling in last year's presidential election.