By Jonathan Marcus
Diplomatic correspondent, BBC News
The 1990 CFE was an effort to limit tanks and other weapons
Russian President Vladimir Putin's threat to freeze compliance on a key arms treaty shows Moscow's frustration at what it believes is the US disregard for its security interests.
Mr Putin has suggested compliance will be suspended on the Conventional Forces in Europe (CFE) treaty until all Nato countries ratify it.
Efforts to update the treaty, one of the crowning achievements of arms control during the Cold War, have led to diplomatic rows between Moscow and the West.
Now it is contributing to a new chill between Russia and the US.
Cold War legacy
President Putin is making a diplomatic point: if the US can abandon treaties - for example its decision to walk away from the Anti-Ballistic Missile Treaty - Russia can do the same.
The apparent row is over the updated version of the 1990 CFE agreement.
But the real issue here is Moscow's growing frustration at what it sees as Washington's determination to pursue its own security interests come what may.
The most recent and divisive irritant is the Bush administration's plan to deploy a very small number of missile interceptors in Poland; an issue which seems to have upset the Kremlin despite strenuous efforts by the Americans to explain the reasoning behind their decision.
The Russian president's comments on CFE - and the threat to potentially abandon it altogether if Nato countries do not endorse it - marks a significant upping of the diplomatic stakes.
The 1990 CFE agreement is an effort to limit the numbers of tanks, aircraft and other offensive weapons that Nato and the Warsaw Pact could deploy across a broad swathe of Europe between the Atlantic and the Urals.
But the collapse of the Soviet Union and the demise of the Warsaw Pact made this kind of bloc-to-bloc agreement outdated.
A new version of the treaty was agreed in 1999 which involves national ceilings on weapons holdings.
Russia has ratified it. But the Nato countries have refused to do so until Russian forces are withdrawn from bases in Georgia and Moldova.