BRUSSELS, Belgium - Russia will demand that NATO drop its secret agreement to defend three Baltic states against any military attack, Russia's envoy to the alliance said Tuesday.

According to confidential U.S. cables released by WikiLeaks, NATO privately decided in January to expand a defense plan for Poland to also cover NATO members Estonia, Latvia, and Lithuania, which border Russia.

The release of the cables is an embarrassment for both Russia and the alliance because it comes at a time of reconciliation between the former Cold War rivals, when both sides have been emphasizing how close their relations have become.

Russian President Dmitry A. Medvedev was meeting with top European Union officials on Tuesday in Brussels, where both parties signed an agreement to clear the way for Russia's accession to the World Trade Organization.

Dmitry Rogozin, Russia's ambassador to NATO, said he would bring up the NATO agreement to defend the Baltic states during Wednesday's meeting of the NATO-Russia Council, a panel set up in 2002 to improve ties between the former Cold War rivals.

"We must get some assurances that such plans will be dropped and that Russia is not an enemy for NATO," he said.

Rogozin said that despite denials by NATO officials, the plan was clearly aimed at his country: "Against whom else could such a defense be intended? Against Sweden, Finland, Greenland, Iceland, against polar bears, or against the Russian bear?"

NATO's core obligation is to defend all its member states, but the alliance had initially not prepared detailed military plans for the defense of Estonia, Latvia, and Lithuania after they joined in 2004.

But after Russia's quick victory in the 2008 war with Georgia, the three nations began pressing for a greater U.S. and NATO presence.

In a January-dated cable posted on the WikiLeaks website, the State Department told its embassies to keep the NATO plan secret because "a public discussion of contingency planning would also likely lead to an unnecessary increase in NATO-Russia tensions."

In another cable, sent to the State Department last December, Paul Teesalu, security director in the Estonian Foreign Ministry, described the NATO defense plan as an "early Christmas present." He said such discussions should be conducted out of the public eye, saying that Estonia was looking for "solidarity, not visibility."