WASHINGTON/MOSCOW (REUTERS) - US President Donald Trump dismissed a Chinese diplomatic effort to rein in North Korea's weapons programme as a failure on Thursday (Nov 30), while Secretary of State Rex Tillerson said Beijing was doing a lot, but could do more to limit oil supplies to Pyongyang.
In a tweet, Mr Trump delivered another insulting barb against North Korean leader Kim Jong Un, who he called "Little Rocket Man" and a "sick puppy" after North Korea test-fired its most advanced missile to date on Wednesday.
Russian Foreign Minister Sergei Lavrov said Washington's approach was dangerously provocative.
Mr Trump's tweets further inflamed tensions reignited this week after North Korea said it had successfully tested a new intercontinental ballistic missile in a "breakthrough" that put the US mainland within range of its nuclear weapons, whose warheads could withstand re-entry into the Earth's atmosphere.
"The Chinese envoy, who just returned from North Korea, seems to have had no impact on Little Rocket Man," Mr Trump said on Twitter, a day after speaking with Chinese President Xi Jinping and reiterating his call for Beijing to use its leverage against North Korea.
Mr Tillerson on Thursday welcomed Chinese efforts on North Korea, but said Beijing could do more to limit its oil exports to the country.
"The Chinese are doing a lot. We do think they could do more with the oil. We're really asking them to please restrain more of the oil, not cut it off completely," Mr Tillerson said at the State Department. China is North Korea's neighbour and its sole major trading partner.
While Mr Trump has been bellicose at times in rhetoric toward North Korea, Mr Tillerson has persistently held out hopes for a return to dialogue if North Korea shows it is willing to give up its nuclear weapons programme.
However, Mr Tillerson may not remain in his job long, with disagreements with Mr Trump over North Korea being one factor.
On Thursday, senior Trump administration officials said the White House was considering a plan to replace Mr Tillerson with Mr Mike Pompeo, the director of the Central Intelligence Agency.
US Defence Secretary James Mattis said he still had confidence in diplomatic efforts on North Korea and that the United States would be "unrelenting" in working through the United Nations.
In spite of Mr Trump's rhetoric and warnings that all options, including military ones, are on the table in dealing with North Korea, his administration has stressed it favours a diplomatic solution to the crisis.
Mr Trump has pledged more sanctions in response to the latest test and, at an emergency UN Security Council meeting late on Wednesday, the United States warned North Korea's leadership would be "utterly destroyed" if war were to break out.
"This administration is focused on one big thing when it comes to North Korea, and that's denuclearisation of the Korean peninsula," White House spokeswoman Sarah Sanders told a regular White House briefing.
"Anything beyond that is not the priority at this point," she said, responding to a question on whether regime change was on the administration's agenda after Mr Trump's recent tweets and a speech by UN Ambassador Nikki Haley.
Mr Lavrov pointed to joint US-South Korean military exercises planned for December and accused the United States of trying to provoke Mr Kim into "flying off the handle" over his missile programme to hand Washington a pretext to destroy his country.
He also flatly rejected a US call for Russia to cut ties with Pyongyang over its nuclear and ballistic missile programme, calling US policy towards North Korea deeply flawed.
In a call with Mr Trump on Thursday, South Korean President Moon Jae In said the missile launched this week was North Korea's most advanced so far, but it was unclear whether Pyongyang had the technology to miniaturise a nuclear warhead and it still needed to prove other things, such as its re-entry technology.
A White House statement said Mr Trump and Mr Moon reiterated their strong commitment to enhancing the deterrence and defence capabilities of the US-South Korea alliance and added: "Both leaders reaffirmed their strong commitment to compelling North Korea to return to the path of denuclearisation at any cost."
North Korea has tested dozens of ballistic missiles under Mr Kim's leadership and conducted its sixth and largest nuclear bomb test in September.
It has said its weapons programmes are a necessary defence against US plans to invade. The United States, which has 28,500 troops in South Korea as a legacy of the 1950 to 1953 Korean War, denies any such intention.
Previous US administrations have failed to stop North Korea from developing nuclear weapons and a sophisticated missile programme. Mr Trump, who has previously said the United States would "totally destroy" North Korea if necessary to protect itself and its allies from the nuclear threat, has also struggled to contain Pyongyang since taking office in January.