HONG KONG (BLOOMBERG) - In supporting a watered-down version of North Korea sanctions, China and Russia had a stern warning for the United States: Don't try to overthrow Kim Jong Un's regime.

The measures passed on Monday (Sept 11) at the United Nations Security Council included reducing imports of refined petroleum products, banning textile exports and strengthening inspections of cargo ships suspected of having illegal materials.

US envoy Nikki Haley called them the "strongest measures ever imposed on North Korea" even though they ended up dropping demands for an oil embargo and freeze on Mr Kim's assets.

More worrisome for China and Russia was Ms Haley's remark that the US would act alone if Mr Kim's regime did not stop testing missiles and bombs.

The UN representatives of China and Russia on Monday reiterated what they called "the four nos": no regime change, no regime collapse, no accelerated reunification, and no military deployment north of the 38th parallel dividing the Korean peninsula.

"The Chinese side will never allow conflict or war on the peninsula," Foreign Ministry spokesman Geng Shuang said in a statement on Tuesday.

The comments in the wake of the sanctions signalled that both China and Russia are only willing to go so far in pressuring Mr Kim to abandon his attempts to secure the ability to strike the US with a nuclear weapon. Both nations have called for dialogue, something US President Donald Trump has resisted.

China and Russia realise their combined effort "works better than individual action", said Peking University history professor Wang Xinsheng. "Both oppose North Korea to become a full-fledged nuclear state, and both think parallel action from the US is needed to affect any change in the situation."

China and Russia - the biggest economic patrons of North Korea - both share the view that North Korea would not give up its nuclear weapons without security guarantees, and they do not see the point of fomenting a crisis on their borders that will benefit American strategic goals.

At the same time, they do not want Mr Kim provoking the US into any action that could destabilise the region.

"Sanctions of any kind are useless and ineffective," Russian President Vladimir Putin told reporters earlier this month at a summit in Xiamen, China. "They'll eat grass, but they won't abandon their programme unless they feel secure."

Russia and China were singled out at a US House Foreign Affairs Committee hearing on Tuesday on financing for North Korea's nuclear programme. Republican Chairman Ed Royce said the US should target Chinese banks, including Agricultural Bank of China and China Merchants Bank, for aiding Mr Kim's regime.

Assistant Treasury Secretary Marshall Billingslea said in prepared remarks to the committee that North Korean bank representatives "operate in Russia in flagrant disregard of the very resolutions adopted by Russia at the UN".

US officials said the new UN sanctions - combined with earlier measures - would cut North Korean exports by 90 per cent, pinching the regime's ability to get hard currency. The textile export ban alone would cost North Korea about US$726 million (S$977 million) a year, the US said.

Still, analysts saw efforts to dilute the original proposal as successful.

"The stiffer sanctions won't change anything in the near term," said Mr Stuart Culverhouse, head of macro and fixed income research at specialist frontier markets investment bank Exotix Capital. "The new embargoes are incrementally tougher, but diplomacy meant they had to be compromised to an extent that they are very unlikely to change minds in Pyongyang."

North Korea has said it will never give up its nuclear weapons unless the US drops its "hostile" policies toward the regime. Mr Kim has claimed the ability to fit a hydrogen bomb onto an intercontinental ballistic missile, but the US military says he has yet to master re-entry and guidance systems that would allow him to target an American city.

Many analysts think Mr Kim will wait until he has mastered his weapons before negotiating, as it would strengthen his hand. It might take tactical nuclear weapons in South Korea - something President Moon Jae In has opposed - to bring Mr Kim to the negotiating table earlier, according to Ms Lee Ho Ryung, chief of North Korean studies at the Korea Institute for Defence Analyses.

"If South Korea, Japan, or both could have the US deploy tactical nuclear weapons, that'll put pressure on Kim to come to dialogue," Ms Lee said. "When competition to have better weapons escalates, it's always the poorer one who gives up."

Mr George Lopez, a former member of the UN Security Council panel of experts for sanctions on North Korea, said that the US should seek unity of message with China and Russia in addition to a unanimous vote on sanctions. The US should look to engage diplomatically to find a level of security that North Korea and its neighbours will be happy with, he said.

"We did it against powers that have thousands of nuclear weapons," Mr Lopez said. "We certainly should be able to do this against a power that has less than two dozen."