Moscow could unilaterally leave the Russian-U.S. Intermediate-range Nuclear Forces Treaty (INF Treaty) on the elimination of intermediate-and shorter-range missiles, Russian Army staff chief General Yuri Baluyevsky said on Thursday.

The decision would depend on Washington’s further actions in the anti-missile defense field, he said.

“The INF treaty has no time limit, but it is possible to leave it, if one of the sides provides convincing proof of the need to,” Baluyevsky was quoted by the Interfax news agency as saying.

“Now, there are such convincing proofs. Many nations are developing and modernizing medium-range missiles,” he said.

“Unfortunately, Russia, by implementing the INF Treaty, has lost many such weapon systems that earlier had been unique,” he added.

“We shall see how our American partners act further. What they are doing at present forming the third missile defense position area in Europe (Poland) eludes any explanation,” Baluyevsky said.

Russia, as the legal successor of the Soviet Union, is a signatory of the INF Treaty adopted in 1987 by the Soviet Union and the United States. Under the treaty, its signatories pledged not to produce, test or deploy medium-range (1000-5000 km) and short-range (500-1000 km) ballistic and ground-based winged missiles.

The INF treaty has no time limits, although each side, with consideration of its sovereignty, has the right to leave the treaty if it concludes that it threatens its vital interests.