The "advanced negotiations" between the United States and Vietnam to share nuclear fuel and technology disrupt international stability, Chinese analysts have said.

"The US is used to employing double standards when dealing with different countries ... as a global power that has promoted denuclearization, it has challenged its own reputation and disturbed the preset international order," said Teng Jianqun, deputy-director of the China Arms Control and Disarmament Association, on Thursday.

The US and Vietnam - two former Cold War foes - are in advanced talks to share nuclear fuel and technology, which could "unsettle" China, The Wall Street Journal reported on Wednesday.

Under the agreement, Hanoi will reportedly be allowed to enrich uranium on its own soil, a move that is also expected to hamper global nuclear nonproliferation efforts.

Officials at the Chinese Ministry of Foreign Affairs have yet to respond to the news.

The latest deal "marked a step backward in Washington's recent nonproliferation efforts", the Journal reported. Since the George W. Bush administration, Washington has been requiring countries interested in nuclear cooperation with the US to renounce the right to enrich uranium for civilian purposes, as the technology also can be used to make atomic weapons.

The Obama administration has accelerated nuclear talks with Hanoi, initiated back in 2001, in recent months.

"If we're able to have US companies and technologies in play in Vietnam, this gives the ability to exert some leverage," the Journal quoted US officials as saying. "If we shut ourselves out, others may have different standards."

Analysts said it was not the first time Washington has ignored international regulations over the issue.

In 2008, the US signed a nuclear technology deal with India, which did not sign the Nuclear Non-Proliferation Treaty and therefore was not entitled to receiving such transfers. The deal was still granted an exemption due to the US insistence.

"Washington thinks that because Asia is much different from the Middle East and will be less concerned about nuclear terrorism, its deal with Hanoi will not attract too much opposition," Teng said.

Beijing will not be directly threatened by the deal but it will still have to be on its guard, analysts said.

"We cannot turn a blind eye to the situation," said Li Qinggong, deputy secretary-general of the China Council for National Security Policy Studies.

US Secretary of State Hillary Clinton said while visiting Hanoi in July that "the Obama administration is prepared to take the US-Vietnam relationship to the next level".

"We see this relationship not only as important on its own merits, but as part of a strategy aimed at enhancing American engagement in the Asia Pacific," she said.

"It is the latest example of the US' renewed assertiveness in South and Southeast Asia", the Journal reported.

"It means the US is strengthening cooperation with Vietnam to contain China. To Washington, the geo-strategic consideration has surpassed nuclear nonproliferation," said Fan Jishe, a researcher of the Institute of American Studies at the Chinese Academy of Social Sciences.

"But the latest development is certainly not going to block China's way forward. It is sad that the US still has a Cold War mentality," Teng said. "On the other hand, China need not panic or raise its voice."