"I think it is a bit close to the rogue states we are discussing," Scheffer told a conference here when commenting on Russia's proposal.

"But it's a bit too early in the day for my final judgment. It is always useful when two presidents are constructively talking to each other on this," Scheffer added.

Earlier on Thursday, Russian President Vladimir Putin proposed to U.S. President George W. Bush at the G8 summit that the United States uses the Azeri radar to replace its plan to station missile interceptors in Poland and a radar in the Czech Republic.

Moscow suspects the shield is aimed at Russia, but Washington says it is to stop missiles from "rogue" states.

However, in a speech to a forum in Brussels, the NATO chief branded NATO-Russia relationship as one of two "challenges" the 26- member military bloc are facing.

"I am disappointed when I hear comments by President Putin and other senior Russian officials which suggest a tendency to look at today's challenges through the lens of the past," he said.

The NATO chief was clearly angered at Russia's warnings that Russian missiles might once again be targeted at Europe, noting such move would be "unhelpful, unwelcome and frankly anachronistic. "

"The NATO Allies and the U.S. have been very frank and open on third site issues. Let's talk, let's engage," he added.

The issue of the Conventional Forces in Europe (CFE) Treaty is another barriers hindering the NATO-Russia ties.

Scheffer said NATO are committed to discussing them.

"NATO's basic approach is clear: this agreement has underpinned European security for the past 15 years, and provides a degree of predictability and transparency that is to everyone's benefit. Let 's do what is necessary to have it ratified as soon as possible," he said.

Earlier in April, Russian President Vladimir Putin froze Moscow 's commitments under CFE Treaty and said Russia could totally quit it altogether if Russia-NATO council failed to find a solution suitable to Moscow.