And that doesn't mean talk hasn't been tough - the US has been speaking forcefully to North Korea all this time, said Ellen Tauscher, former USA under secretary of state for arms control and global security under President Barack Obama.
A White House statement said Trump and President Emmanuel Macron had discussed "the increasingly unsafe situation associated with North Korea's destabilising and escalatory behaviour".
As the crisis has unfolded, Trump has alternated praising China for its help and chiding it for not doing more.
North Korea has lashed back at the US following President Donald Trump's latest warnings.
"Military solutions are now fully in place, locked and loaded, should North Korea act unwisely".
Trump said he would consider negotiations with North Korea and declined to discuss the possibility of a preemptive strike against Pyongyang.
The comments came after Trump unleashed a slew of fresh threats against North Korea on Friday, declaring the US military "locked and loaded".
"Hopefully it will all work out", he told reporters in Bedminster, New Jersey.
Xi Jinping, the leader of North Korea's key ally China, urged Trump on Saturday to avoid rhetoric that could inflame tensions, after the USA leader ramped up his warnings to Pyongyang, saying the Stalinist regime would "truly regret" taking hostile action against the United States. The U.S. hasn't taken any public steps to prepare for hostilities such as evacuating Americans from Seoul, which is within range of North Korean artillery, or moving ships, aircraft or troops into position for an imminent response. "North Koreans are not suicidal".
The two leaders also reiterated a commitment to the denuclearization of the Korean Peninsula.
Professor Lucas said: "The Chinese and the U.S. have been talking behind the scenes for months about what to do". He added that China and North Korea understand that Trump "is actually prepared to use military force - credibility that prior administrations simply lacked".