New York - US Secretary of State Rex Tillerson appealed to the international community, especially Russia and China, to stop the spread of nuclear weapons, calling North Korea a case study of the failure to prevent rogue states from obtaining weapons of mass destruction.US-Russian relations are at a low point, but Tillerson recalled the co-operation between Washington and Moscow during the Soviet era, despite their Cold War rivalry, on measures to stop the threat of nuclear weapons proliferation. And he said "we should do so again"."We especially ask Russia to examine how it can better support global non-proliferation efforts," Tillerson said. "If Russia wants to restore its role as a credible actor in resolving the situation with North Korea it can prove its good intentions by upholding its commitments to establish international efforts on nuclear security and arms control."As for China, he said Beijing's co-operation is essential to prevent "a catastrophe" and conflict on the Korean Peninsula. If China truly wants to denuclearise the peninsula, he said it should work "to put the kind of pressure on North Korea that can change its strategic calculation before it's too late".Tillerson said North Korea "is a case study in why nations must work to preserve and strengthen global non-proliferation norms".North Korea joined the Nuclear Non-proliferation Treaty in the mid-1980s but it "cheated" and was never held accountable, he said. It withdrew from the treaty in 2003 and carried out its first underground nuclear test in 2006.Tillerson spoke on Thursday at a ministerial meeting of the UN Security Council called by the United States on "the acute threat" posed by the proliferation of nuclear, chemical and biological weapons. It cited three countries in a note to council members that have been targeted by council resolutions - North Korea, Iran and Syria.'Pariah states'Russia's UN Ambassador Vassily Nebenzia took issue with the meeting, saying a discussion on non-proliferation "should be general, not pegged to someone's idea of 'pariah states'."He said a US "concept note" sent to council members before the meeting "artificially links three country situations which have absolutely nothing to do with each other".He said "further prospects in the field of non-proliferation cannot be considered in isolation from the overall security" situation. "This means taking into account all factors that affect security - "first and foremost" the US deployment of the Terminal High-Altitude Area Defence System, also known as THAAD, and "Nato's joint nuclear mission".Russia and China again urged adoption of their freeze-for-freeze proposal that would halt North Korean nuclear and missile tests in exchange for the US and South Korea stopping their joint military exercises. But the Trump administration has rejected it.