US President Barack Obama's team has scored a key foreign policy win and bolstered international stability with an apparent new nuclear arms reduction deal with Russia, according to analysts.

In Moscow, a Kremlin source told AFP Wednesday that Russia and the United States have agreed "all the documents" for a successor to the landmark 1991 Strategic Arms Reduction Treaty (START) and will likely sign it in Prague.

Czech TV Nova said it would be April 8.

US officials said "technical details" still need to be worked out, but that US, Russian and Czech officials were considering Prague as a venue for signing the eventual treaty to replace the one that expired in December.

Jeffrey Lewis, a nuclear weapons specialist at the New America Foundation, said the deal "shows we can still do arms control," adding the United States has negotiated nothing so complex in over than a decade.

The deal provides for modest cuts but at least continues "the momentum of reductions," after the George W. Bush administration gutted the US capacity to conducts arms control negotiations, he said.

"This (new treaty) is not the end-all and be-all of arms control. The fact that they could do it at all is what's impressive," Lewis told AFP.

The Center for American Progress (CAP), a think tank, said in an e-mail that the reported deal "marks an historic achievement that will increase the safety and security of the United States and our allies."

It "reduces the threat of nuclear war, marks a significant step in advancing President Barack Obama's vision of a world without nuclear weapons, and is a tangible result" of Obama's bid to improve ties with Russia, CAP added.

In Prague last April, Obama gave a major speech calling for a world free of nuclear weapons, while acknowledging he may not live to see that goal achieved.

"The new START agreement also lays the groundwork for the United States and Russia to begin additional negotiations to hammer out an even more far-reaching agreement," the research center said.

Analysts said it could help pave the way, for example, for a deal that includes cuts in tactical or so-called battlefield nuclear weapons.

Analyst Miles Pomper called the deal "a significant foreign policy achievement," as it comes before a nuclear security summit next month and the review conference for the Nuclear Non-Proliferation Treaty (NPT) in May.

He said it would in particular give "some positive momentum" to the NPT conference, which requires nuclear powers like Russia and the United States to show progress on disarmament.

Pomper, with the James Martin Center for Non-proliferation Studies, said states like Iran and North Korea will now find it harder to resist demands for more stringent measures through the NPT.

He said the deal may also further boost growing Russian support for US-led efforts to impose tougher UN sanctions against Iran over its failure to comply with demands to curb its uranium enrichment program.

"It can help," Pomper told AFP.

Obama and Russian President Dmitry Medvedev set a goal in July of slashing the number of warheads on either side to between 1,500 and 1,675 and the number of "carriers" capable of delivering them to between 500 and 1,100.

The United States has said it currently has some 2,200 nuclear warheads, while Russia is believed to have about 3,000.

However, specialist Lewis said the Russian number is actually closer to the US figure, and in any case the actual nuclear weapons reductions are limited.

"We might download some more warheads but we're not going to cut up any delivery vehicles as a result of this treaty," Lewis said, referring to long-range rockets and bombers.

"It is underwhelming," he said. "The gain here is in convincing the Russians to leave in place some of the START verification measures that we lost in December."

Mikhail Margelov, an influential player in the upper house of Russia's parliament, suggested the new treaty would contain a link between Moscow's resistance to US missile defense and cuts in strategic offensive weapons.

Analysts said US Republicans enamored of missile defense may try to deny the Obama administration the two-thirds majority it needs in the Senate for the START treaty to pass.