President Vladimir Putin on Tuesday said Russia would not interfere in Ukraine's aspirations to join NATO but might be forced to aim missiles at its neighbour if Ukraine hosted Western missile-defence facilities.
Speaking after talks with Ukrainian President Viktor Yushchenko at the Kremlin, Putin said that joining NATO was Kiev's prerogative, although he warned it would "limit Ukraine's sovereignty."
"We don't have a right to and we will not interfere in" Ukraine's efforts to ensure its own security, Putin said.
However Putin warned that if Ukraine followed the lead of ex-Soviet-bloc countries in eastern Europe and hosted missile-defence facilities "to neutralize our nuclear potential" that Russia would be forced to respond.
"It is terrible even to think that in response to this… Russia cannot theoretically exclude aiming our offensive-missile systems at Ukraine," Putin said.
Moscow sees the expansion of NATO, as well as the deployment of a US anti-missile shield in central Europe, as threats to Russian security.
Putin last year threatened to aim missiles at European cities if elements of the anti-missile shield were deployed in Poland and the Czech Republic.
Earlier Tuesday the Kremlin said Putin had signed a law that reduces military cooperation, suspending the use of two radars in Ukraine by Russian forces.
Kiev hopes NATO will approve a Membership Action Plan for Ukraine — a formal step towards membership — at the alliance's Bucharest summit on April 2-4.
Yushchenko defended his government's moves towards joining the alliance and insisted that they were not aimed against Russia.
"We follow the principle that any nation has the right to define its own security," he said. "Our constitution does not allow deployment by a third country or bloc on Ukrainian territory.
"Everything that Ukraine does in a western direction is not by any means aimed against some third country, and not at all against Russia," he said.
