(Adds Yushchenko comments, Kouchner)
By Elizabeth Piper and Yuri Kulikov
KIEV, Aug 27 Ukrainian President Viktor Yushchenko on Wednesday called Russia's decision to recognise two Georgian rebel regions unacceptable and threatened to raise the issue of a rent increase at a base for the Black Sea Fleet.
Saying any country which was not part of international security agreements could be next to feel Russia's military might, Yushchenko said Ukraine must increase its defences and push its bid for membership of the NATO military alliance.
"We regret this decision, for Ukraine it is unacceptable and therefore we cannot support this position," Yushchenko told Reuters in an interview.
"What has happened is a threat to everyone, not just for one country. Any nation could be next, any country. When we allow someone to ignore the fundamental right of territorial integrity, we put into doubt the existence of any country."
Russia announced on Tuesday that it recognised the breakway Georgian provinces of South Ossetia and Abkhazia as independent states, provoking widespread international condemnation.
The Russian military launched an overwhelming counter-attack earlier this month after Georgia tried to regain control of South Ossetia by force and Moscow's troops are still occupying some areas of Georgian territory.
Some in Ukraine fear it could be the next target of Russia's campaign to reassert influence over countries it long dominated in the Soviet Union, with Moscow well placed to foment separatist feelings in Ukraine's Russian-speaking south.
In Paris, French Foreign Minister Bernard Kouchner said Russia might have its eye on countries such as Ukraine and neighbouring Moldova after the conflict in Georgia.
"I repeat that it is very dangerous, and there are other objectives that one can suppose are objectives for Russia, in particular the Crimea, Ukraine and Moldova," he told Europe 1 radio.
BLACK SEA FLEET
In remarks bound to anger Moscow, Yushchenko said Ukraine had leased the base at the Crimean port of Sevastopol for Russia's Black Sea fleet at below market rates and it was time to think about raising the price.
"(We need to) raise the question about the lease payment, and new financial conditions because those old conditions were set when there was no market for land deals ... and assets which the Russian fleet uses were not considered as assets which must be paid for," he said.
Russian Deputy Foreign Minister Grigory Karasin earlier on Wednesday warned Ukraine against stirring tensions.
"Some Ukrainian politicians are working hard to trigger a crisis in our relations. They sort of tease us hoping that we... will respond toughly which, they think, will raise the wave of 'healthy nationalism'. This is a cynical and dangerous game," he said on the ministry's web site www.mid.ru.
Under a 1997 pact, Russia leases the Sevastopol base until 2017 for an annual fee of $98 million.
When Ukraine raised the question of increasing the rent almost three years ago after Russia demanded a nearly five-fold increase in gas prices, Moscow warned Kiev it could reignite a potentially dangerous border row.
Mainly Russian-speaking Crimea, in Ukraine's south, was granted to the Ukrainian Soviet Republic in 1954, but Sevastopol still has a powerful hold over many in Russia as a symbol of Russian military glory.
Russia used ships from the Black Sea Fleet to land troops in Georgia and patrol its waters. And the first boat to return last week was welcomed by cheering pro-Russian crowds.
Yushchenko hinted the base lease might not be renewed.
"We need to prevent Ukraine becoming involved in a military conflict ... We don't intend to allow troops which could be used in military action with a third or fourth country to use our territory as a base," he said.
Yushchenko again said Ukraine needed to enter NATO for its own security.
"Our policy has not changed. We aim to enter the pan-European system of security because we are convinced that today there is no other alternative way of protecting Ukraine's territorial integrity, her sovereignty," he said.
(Additional reportingby Oleg Shchedrov in Moscow)
(Writing by Elizabeth Piper; editing by Robert Hart)