NEW YORK: North Korean leader Kim Jong-un is "begging for war" with his latest and most powerful nuclear bomb test, the US envoy to the United Nations has said.
Nikki Haley told an emergency meeting of the Security Council in New York that the US did not want a war but its patience was "not unlimited". The US will table a new UN resolution shortly to toughen sanctions.
However, Russian President Vladimir Putin on Tuesday called sanctions "useless, ineffective and exhausted".
China, the North's main ally, has called for a return to negotiations and Switzerland has offered to mediate.
Meanwhile South Korea's navy carried out live-fire naval drills on Tuesday, warning that if the North provoked them "we will immediately hit back and bury them at sea", reported Yonhap news agency.
It comes a day after the South's military simulated a missile attack on the North's nuclear test site.
Reports suggest the North is preparing new test missile launches.
On Sunday, it tested a bomb underground, which was thought to have a power range from 50 kilotonnes to 120 kilotonnes. A 50kt device would be about three times the size of the bomb that destroyed Hiroshima in 1945.
German Chancellor Angela Merkel said she would press for tougher EU sanctions on North Korea, agreeing with US President Donald Trump by phone on the need for stricter measures.
Japan is planning, in the event of war, for a mass evacuation of nearly 60,000 Japanese citizens currently living in or visiting South Korea, Nikkei Asian Review reports.
Ms Haley argued that only the strongest sanctions would enable the problem to be resolved through diplomacy.
"War is never something the United States wants," she said. "We don't want it now but our country's patience is not unlimited."
China's envoy to the UN, Liu Jieyi, reiterated a call for all sides to return to negotiations.
"The peninsula issue must be resolved peacefully," he said. "China will never allow chaos and war on the peninsula."
Speaking in Berne, Swiss President Doris Leuthard pointed to her country and Sweden's long record in neutral and discreet diplomacy.
"I think it really is time for dialogue," she said. "We are ready to offer our role for good services as a mediator. I think in the upcoming weeks a lot will depend on how the US and China can have an influence in this crisis."