Nato has reacted cautiously to a Russian offer to use a radar facility in Azerbaijan as part of a joint missile defence system with the US.
Mr De Hoop Scheffer criticised Russia over its missile aim claim
The alliance's secretary-general, Jaap de Hoop Scheffer, welcomed the proposal as a break with the "anachronistic" rhetoric between the two countries.
But he warned the system would probably be too close to the "rogue states" it is designed to defend against.
Russia's President Vladimir Putin made the offer at the G8 summit on Thursday.
Mr Putin presented his proposal to US President George W Bush as an alternative to US plans to deploy missile defences in Poland and the Czech Republic.
Speaking to the press on Friday at the end of the summit, Mr Putin also suggested that the US should consider locating the missile defence interceptors in Nato member Turkey, in Iraq or even on sea platforms.
Russia has repeatedly dismissed US claims the defence shield is only targeting so-called rogue states, such as Iran and North Korea, and in response has said it may aim its missiles at Europe once more.
Mr Bush described the most recent Russian proposal as "interesting" and said US officials would study it.
But during a brief visit to Poland on Friday he made it clear that both countries were still planning to go ahead with the proposed European missile defence shield.
Mr Bush praised his Polish counterpart, Lech Kaczynski, for supporting installing interceptors on Polish soil and said the shield would enhance "the security of Poland and the security of the entire continent against rogue regimes".
Both Mr Bush and Mr Kaczynski stressed the system was not directed at Russia. "We would welcome Russian cooperation in missile defence," Mr Bush said.
Mr De Hoop Scheffer reacted positively to Russia's proposal for a joint defence system.
"I hope that what we are seeing... is a signal that everybody will start talking to everybody once again on this important subject of missile defence," he told a defence conference in Brussels.
"We need to get on with addressing together the 21st Century's security challenges, rather than resurrecting those from the past."
Mr De Hoop Scheffer added that he had been concerned by Russia's threat to re-direct its missiles at Europe.
"Warnings that Russian missiles might once again be targeted at Europe are unhelpful, unwelcome and, frankly, anachronistic," he said.
However, Nato's leader said Russia's alternative to the US missile defence shield had its weaknesses.
"I think it is a bit close to the rogue states we are discussing," he said.
"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."
Azerbaijan's foreign minister, Elmar Mamedyarov, welcomed Russia's plan, describing it as a move that would bring more stability to the region.
Mr Mamedyarov said his country had already held "rudimentary consultations" with US officials.
The Qabala radar facility in the north of Azerbaijan is leased by the Russian military and can scan the Indian Ocean, the Middle East and most of North Africa.