The United States has called for more transparency from Russia and China regarding their nuclear programs, as diplomats from five major nuclear powers meet in Beijing.
The two-day conference that opened on January 30 is aimed at preventing the further proliferation of nuclear weapons. Aside from Beijing, Moscow, and Washington, diplomats from London and Paris are also participating.
Britain, China, France, Russia, and the United States are the five permanent members of the UN Security Council, and all of them are nuclear-armed powers.
The meeting comes as a major arms control treaty between the United States and the Soviet Union -- the Intermediate-Range Nuclear Forces (INF) Treaty -- is on the verge of collapse.
U.S. Undersecretary of State Andrea Thompson said in opening remarks at the meeting that there were "uneven results" in efforts to increase transparency under the Treaty on the Nonproliferation of Nuclear Weapons, also known as the NPT.
"We previously agreed to set [a] format for reporting, but the gap between the reports of the United States on the one hand, and Russia and China on the other, is great," Thompson said.
The 1987 INF Treaty bans production, testing, and deployment of land-based cruise and ballistic missiles with a range of 500 to 5,500 kilometers. The agreement was the first of its kind to eliminate an entire class of missiles and is widely seen as a cornerstone of arms control stability, in Europe and elsewhere.
But Washington and NATO now accuse Russia of breaching the treaty by developing the 9M729 cruise missile, also known as the SSC-8.
Moscow denies that the missile is violating the INF treaty and accuses the United States in turn that it wants to abandon the pact so it can start a new arms race.
Washington has said that if Russia does not return to compliance, it will start the six-month process of leaving the pact from February 2.
U.S. President Donald Trump has also cited concerns that Washington is restricted by the bilateral pact while nuclear-armed countries such as China are not.
Earlier this month, talks in Geneva between senior diplomats of Russia and the United States ended without result.
Thompson told the Beijing meeting that the United States wanted to discuss "how we can enhance transparency with a view to reassuring others of the very real steps we are taking to ensure full and verifiable compliance with our arms control nonproliferation and disarmament commitments and obligations."
Deputy Russian Foreign Minister Sergei Ryabkov pointed at "the spread of unilateral attitudes" as a threat to nuclear nonproliferation.
"Many issues continue to be unsettled due to the lack of political will," Ryabkov also said, adding that there was an "evident lack of mutual trust" between the five NPT states.
Ryabkov and Thompson were expected to meet on the sidelines of the conference in Beijing for discussions on the INF impasse.