By Gleb Stolyarov
BOGORODSKOYE, Russia (Reuters) - Moscow responded coolly Wednesday to a U.S. invitation to monitor missile-defense flight tests, saying the gesture would not dispel its concerns that a planned NATO missile shield in Europe would compromise Russia's security.
Foreign Minister Sergei Lavrov's remarks underscored the uphill battle the U.S. administration faces in convincing the Kremlin to drop its complaints about an anti-missile system Washington says poses no threat to Russia.
A Pentagon official said Tuesday the United States had invited Russia to use its own radars and other sensors to monitor one or more U.S. missile interceptor flight tests.
Lavrov made clear the offer fell far short of Moscow's calls for a role in planning a missile shield and a binding guarantee that the system would not weaken Russia.
"We are being invited to monitor the realization of a plan that we see as creating a risk to our forces of deterrence," Lavrov told reporters when asked about the invitation.
The United States says the shield is not intended to counter Russia's huge arsenal, but is needed to protect against missiles fired by countries with smaller arsenals such as Iran.
Persistent tension over the plan has undermined efforts to build on recent improvements in ties between the former Cold War foes.
Moscow says the system, due to be fully deployed by 2020 with interceptor missiles and radars at sea and in several European countries, would weaken Russia if it is able to shoot down the nuclear missiles Moscow relies upon as a deterrent.
The idea of the invitation is to let Russia measure the performance of interceptors and show they are not a threat.
Lavrov reiterated Russia's complaint that the United States is pushing ahead with its own plans instead of giving Moscow a say in how a European missile shield should look.
"It would be better to ... first collectively create a missile defense architecture that would be guaranteed to be directed outside Europe and would not create threats for anyone inside Europe -- and only then to start putting this system in place and inviting one another to monitor," he said.
Russia also is demanding binding guarantees that the system will not threaten it. The chief U.S. negotiator on missile defense, Undersecretary of State Ellen Tauscher, said Tuesday the United States is prepared to offer written assurances but not legally binding commitments.
(Reporting By Gleb Stolyarov; Writing by Alexei Anishchuk; Editing by Steve Gutterman and Peter Graff)