South Korea said yesterday it was talking to the United States about deploying aircraft carriers and strategic bombers to the Korean peninsula after signs North Korea might launch more missiles in the wake of its hydrogen bomb test.
Officials said activity around missile launch sites suggested North Korea planned more missile tests.
In view of this, the United States yesterday launched a bid at the UN Security Council to quickly slap the "strongest possible measures" on North Korea in response to its sixth and most powerful nuclear test, but China and Russia argued that diplomatic talks were needed to address the crisis.
US Ambassador Nikki Haley said Washington will present a new sanctions resolution to the council to be negotiated in the coming days, with a view of voting on it next Monday.
"Only the strongest sanctions will enable us to resolve this problem through diplomacy," Haley told an emergency council meeting called by the United States, Britain, France, Japan and South Korea.
Declaring that "enough is enough," Haley said incremental sanctions imposed on Pyongyang since 2006 had failed and accused North Korean leader Kim Jong-Un of "begging for war."
Haley did not spell out what measures Washington was seeking, but diplomats said they could target oil supplies to North Korea -- potentially dealing a major blow to the economy.
New sanctions could also seek to curb tourism to North Korea and ban North Korean laborers sent abroad, mostly to Russia and China, to earn hard currency for the regime, diplomats said.
The draft text was expected to be presented to the 14 other council members on Tuesday as the United States sought to respond quickly to reports that North Korea was preparing another missile launch.
"We have continued to see signs of possibly more ballistic missile launches. We also forecast North Korea could fire an intercontinental ballistic missile," Jang Kyoung-soo, acting deputy minister of national defense policy, told a parliament hearing on Monday.
North Korea tested two ICBMs in July that could fly about 10,000 km (6,200 miles), putting many parts of the US mainland within range and prompting a new round of tough international sanctions.
South Korea's air force and army conducted exercises involving long-range air-to-surface and ballistic missiles yesterday following the North's nuclear test on Sunday, its joint chiefs of staff said in a statement.
In addition to the drill, South Korea will cooperate with the United States and seek to deploy "strategic assets like aircraft carriers and strategic bombers", Jang said.
South Korea's defence ministry also said it would deploy the four remaining launchers of a new US missile defence system after the completion of an environmental assessment by the government.
The rollout of the controversial Terminal High Altitude Area Defense (THAAD) system at a site south of the South Korean capital, Seoul, is vehemently opposed by neighbouring China and Russia, had been delayed since June.
Furthermore, US President Donald Trump and South Korea's leader Moon Jae-In spoke on the phone Monday and agreed to remove limits on the payload of the South's missiles, Seoul's presidential office said.
Seoul was previously restricted to a maximum warhead weight of 1100 pounds (500 kilograms) on its ballistic missiles, according to a bilateral agreement with the United States signed in 2001.
At the UN, China's ambassador Liu Jieyi warned that the crisis was worsening and emphasized the need for dialogue and a diplomatic solution.
"China will never allow chaos and war on the (Korean) peninsula," he asserted.
Liu urged the parties to agree to a Chinese-Russian plan calling for the North to freeze its missile and nuclear tests and the United States and South Korea to suspend joint military exercises.
Haley rejected the proposal as "insulting."
Haley reiterated US threats to impose sanctions on countries that conduct trade with North Korea, saying these nations will be seen as "giving aid to their reckless and dangerous nuclear intentions."
That could have major reverberations: China is the largest trading partner of both the North and the United States.
Asked about Trump's threat to punish countries that trade with North Korea, Chinese Foreign Ministry spokesman Geng Shuang said China has dedicated itself to resolving the North Korean issue via talks, and China's efforts had been recognised.
"What we absolutely cannot accept is that on the one hand (we are) making arduous efforts to peacefully resolve the North Korean nuclear issue, and on the other hand (our) interests are being sanctioned or harmed. This is both not objective and not fair," he told a regular briefing.
While South Korean President Moon Jae-in and Japanese Prime Minister Shinzo Abe agreed yesterday to work with the United States to pursue stronger sanctions, Russia voiced scepticism.
Russia said it would study the new US proposals for sanctions, but again stressed those measures alone would not resolve the crisis.
Earlier, Russian Deputy Foreign Minister Sergei Ryabkov told a BRICS summit in China that sanctions on North Korea had reached the limit of their impact. Any more would be aimed at breaking its economy, so a decision to impose further constraints would become dramatically harder.
North Korea said it tested an advanced hydrogen bomb for a long-range missile on Sunday, prompting a warning of a "massive" military response from the United States if it or its allies were threatened.
"We are not looking to the total annihilation of a country, namely North Korea," US Defense Secretary Jim Mattis said after meeting Trump and his national security team.
"But as I said, we have many options to do so."
Trump has previously vowed to stop North Korea developing nuclear weapons and said he would unleash "fire and fury" if it threatened US territory.