Russia has provided notice that it is withdrawing from the Treaty on Conventional Armed Forces in Europe (CFE). (The New York Times story is here; the Kremlin press release is here; the State Department press release is here; and the OSCE press release is here.) In accordance with Article 19(2) of the Treaty, Russia's withdrawal (which it terms a "suspension") will take effect in 150 days. Russia's action follows the failure of June's Extraordinary Conference of the States Parties to the CFE Treaty (discussed here), which Russia had requested because "of the serious problems that have arisen with the NATO nations' implementation of the Treaty as a result of its enlargement and NATO foot-dragging on ratification of the Agreement on the Adaptation of the CFE Treaty, signed in 1999." Russia's action is clearly an attempt to pressure the United States and other NATO countries into altering their negotiating positions before the 150-day period passes. We'll see whether it works.
UPDATE (7/16): At Opinio Juris, Duncan Hollis suggests that the Russian Government's attempt to describe its actions as a "suspension" rather than a "withdrawal" may, in fact, have some legal basis. If that is so, the legal consequences of a suspension would obviously be different from those that stem from a withdrawal. As Duncan recognizes, however, such an argument has little, if any, support in the text of the Vienna Convention on the Law of Treaties and no support in the text of the CFE Treaty. Why did the Russians use the term "suspension" then? The Russian choice of words was, no doubt, politically motivated - perhaps to distinguish its action from the U.S. withdrawal from the ABM Treaty and perhaps to send a more temperate signal (to NATO, to the press) than that connoted by the word "withdrawal." The obfuscatory choice also gives the Russians some considerable leeway down the road (should the 150-day period pass) to characterize their CFE Treaty status as they see fit. In this sense, the particular legal term of art used (withdrawal v. suspension) was a tactical choice; its relevance lies in the signal it sends now and the options it leaves open for later. It doesn't matter really that there might be no formal legal basis for a suspension. What matters is whether the relevant parties can come to an accommodation. If not, then a "suspension" is as good as a "withdrawal."