Ukraine`s pro-Western leaders, brought to power by the 2004 "Orange Revolution" and committed to seeking NATO membership, have been increasingly at odds with Russia over foreign policy.
Yushchenko, like the United States, backs Georgia in its conflict with Russia over separatist South Ossetia.
He further enraged Moscow this week by ordering restrictions on the movement of ships in the Black Sea fleet, based in the Crimean port of Sevastopol. Russia`s military vowed to disregard the rules, saying the fleet answered only to Russia`s president.
Russia`s conflict with Georgia over the separatist region of South Ossetia has prompted suggestions that pro-Russian nationalism in the Crimea, strong in the 1990s, could be rekindled and undermine the authority of the Ukrainian state.
Crimea, part of Russia from the late 18th century, was handed to Soviet Ukraine by Kremlin leader Nikita Khrushchev in 1954. It became part of independent Ukraine in 1991 when the Soviet Union fell.
Valentin Nalivaichenko, acting chairman of Ukraine`s SBU security service, said latent nationalism in Crimea could not be compared with South Ossetia`s longstanding rebellion that ultimately led to the conflict between Georgia and Russia.
"I am certain that such a scenario is not possible in Ukraine," he told the weekly Zerkalo Nedeli.
"Prosperity, peace and calm in Crimea is the very foundation on which the interests of Ukraine and neighboring Russia coincide. Everything else is of secondary importance."
Nalivaichenko said Ukraine had taken legal action to hobble nationalist groups in Crimea. "If we complete this stage and go on to the next one, we can be confident that there will be no Russian, or any other, destabilization scenario in Crimea."
LEASE TO RUN OUT
Russia`s Black Sea Fleet is based in the port of Sevastopol under a leasing agreement due to expire in 2017. Yushchenko has made plain that the lease will not be renewed and talks should focus on overseeing the fleet`s orderly departure.
Outbursts of pro-Russian nationalism in the 1990s prompted authorities in Kiev to reduce local autonomy.
Kiev`s jurisdiction over Crimea, populated mainly by ethnic Russians, remains a highly sensitive issue among nationalists in Moscow who periodically call for Sevastopol -- or the entire peninsula -- to revert to Russian jurisdiction.
In a statement on his website late on Friday, Yushchenko said his backing for Georgia was based on preserving the country`s territorial integrity and similar concerns in Ukraine.
Disagreements with Russia over the fleet, he said, could only be settled through a formal agreement.
"I have therefore sent an urgent proposal to the president of Russia to start talks on signing an agreement that would regulate our relations in the event of military action like that which we saw at the beginning of August," he wrote.
"In other words, we need to come up with clearer rules that would ensure Ukraine`s national security in such situations."
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