- No-go: NATO expansion -

In draft treaties for the Americans and NATO in December, Russia demanded that the US prevent eastward expansion of NATO into any former Soviet countries like Ukraine.

NATO's response, leaked to Spanish newspaper El Pais this week, showed that the alliance is sticking to its "open door policy".

It insists on "all states respecting the right of other states to choose or change security arrangements" and demanded Russian troops withdraw from Crimea, annexed from Ukraine in 2014, as well as parts of Georgia and Moldova.

President Vladimir Putin has in turn slated the "unwillingness of NATO to adequately respond to the well-founded Russian concerns".

"You now have enough states in Scandinavia and Eastern Europe hostile to these Russian demands (to be) able to block any progress on any of this," Alexander Clarkson of King's College London told AFP.

"They completely correctly, in their own self-interest, will not let the Americans or the other EU states... cede towards the Russians," he added.

- 'Indivisible security' -

NATO's language on security arrangements is drawn word-for-word from past agreements with Russia like the 1999 Charter for European Security.

Meanwhile Moscow has justified its demands with those texts' commitments that signatories "will not strengthen their security at the expense of the security of other states".

"The US and NATO responses to our proposals... demonstrate serious differences in the understanding of the principle of equal and indivisible security," Russian Foreign Minister Sergei Lavrov wrote this month to the US and other NATO countries.

That specific term appears to itself be a point of difference between the two sides.

In its response to the Russian security demands, Washington had said it was "prepared for a discussion of the indivisibility of security -- and our respective interpretations of that concept".

- Reducing conventional forces -

Russia's draft agreement with NATO also included a clause that would ban NATO forces and weapons anywhere east of the alliance's position in 1997.

That would cut out nations once dominated by the Soviet Union like Poland, the Czech Republic and the Baltic states.

In response, NATO said Russia should return to the terms of the Treaty on Conventional Armed Forces in Europe (CFE) limiting equipment like tanks, artillery and helicopters, which it suspended in 2007.

- Missiles -

Russia suggested to the US that both nations should be banned from deploying short- or intermediate-range missiles outside their own territory, or within range of the other's territory.

Washington said it was "prepared to begin discussion... on arms control" for such missiles.

But it also said it was worried about Russian breaches of the Intermediate Range Nuclear Forces Treaty (INF) before it expired in 2019.

That 1987 agreement banned both sides from having conventional or nuclear missiles with ranges between 500 and 5,500 kilometres (310-3,400 miles).

The US is also "prepared to discuss... a transparency mechanism to confirm the absence of Tomahawk cruise missiles" at missile defence sites in Romania and Poland, Washington said -- although it demanded similar openness on two Russian bases.

- Flashpoints -

Besides the sorest points, both Russia and NATO are open to new steps to avoid unwanted military incidents -- so-called "de-confliction".

That could include setting up hotlines between capitals and finding new ways to skirt clashes in the air and at sea, like advance warnings or limits on exercises.

"Those documents do contain elements that can provide a basis for an off-ramp for the Russians, if they want to take it. And we can't know that," said Clarkson.

But Bruno Tertrais of France's Foundation for Strategic Research warned that the West's position "has no concessions on the key principles" raised by Russia.

If Moscow were to accept a limited agreement "it would be a major Russian about-face", he added.