The country's top general said Tuesday that U.S. missile defense plans were directed against Russia and differences over the issue are holding up an arms treaty with Washington, news agencies reported.

The remarks revived questions about the chances for an agreement soon on a successor to a Cold War-era nuclear weapons reduction treaty that expired in December.

"The development and establishment of the [U.S.] missile shield is directed against the Russian Federation," said Nikolai Makarov, the armed forces chief of staff, Interfax reported.

U.S. President Barack Obama pleased Russia by scrapping the previous administration's plans to deploy elements of a missile shield in Poland and the Czech Republic, which was bitterly opposed by Moscow.

Makarov said Russia still had serious concerns about Obama's revised plans, which are based on sea- and land-based missile interceptors in Europe, despite American insistence that they are no threat to Russia.

"Despite the declarations of those statesmen who say that, on the contrary, it provides for our security, that's far from the case," he said, RIA-Novosti reported. "For this reason it's completely understandable that we have a very negative attitude about this issue."

Russian and U.S. officials have said they are close to agreement on a successor to the 1991 Strategic Arms Reduction Treaty, or START I, which was a key part of efforts to improve relations.

But Makarov said differences over missile defense were among reasons "why we have not yet reached a signing of this agreement," RIA-Novosti reported.

His comments also raised questions about whether Russia is ready to sign a treaty that makes little or no mention of missile defense — an issue that Moscow says is inextricably linked with offensive missiles.