Russian President Dmitry Medvedev has said to the Ukrainian President Viktor Yuschenko that Ukraine's aspiration to be introduced to NATO is a breach of the friendship treaty between the two neighbor countries.

"The Amity and Collaboration Treaty stipulates that no country will pose a threat to the other country's security," Lavrov quoted Medvedev words as saying in a meeting with Yuschenko in St. Petersburg city.

"The Russian president added that "Ukraine's future possible membership in this Alliance prompts more and more problems and pushes one to think about Russia's security," the minister told to the journalists.

Medvedev also admitted to Yuschenko that "it is very important to respect our common legacy and to be guided by existing contracts when we solve every issues that exist in our relations and that appear in the relations our countries have with other countries of the world," Lavrov noted.

The issue is primarily about respect for the friendship treaty, which was conducted as a package with the contract on the presence of the Black Sea Fleet on the Ukrainian territory, the minister said.

"Unilateral actions taken in violation of the spirit of the agreement and the treaty do not add to stability in our relations," Lavrov noted.

Medvedev alsomentioned to Yuschenko that the resolution of the issue concerning the normal functioning of the Black Sea Fleet was provided for in existing agreements, and that one cannot substitute work on the resolution of still-unresolved issues with unilateral acts, the minister said.