Steve G. wrote:
One of the big problems is that Russia already has a BIG military presence in Crimea as part of their Black Sea fleet.

A year after its war with Georgia, Russia is engaging in an increasingly hostile standoff with another pro-Western neighbor, Ukraine.

Protesters in Kiev, Ukraine’s capital, held posters this week that were critical of President Dmitri A. Medvedev of Russia.

Russian s-e-amen [forum filter] marched during a military parade in late July in Sevastopol, a port city in Ukraine where Russia has long maintained a naval base and much of the population has Russian ties.

Relations between the two countries are more troubled than at any time since the Soviet collapse, as both sides resort to provocations and recriminations. And it is here on the Crimean Peninsula, home to a Russian naval base, where the tensions are perhaps most in danger of bursting into open conflict.

Late last month, the Ukrainian police briefly detained Russian military personnel who were driving truckloads of missiles through this port city, as if they were smugglers who had come ashore with a haul of contraband. Local officials, it seemed, were seeking to make clear that this was no longer friendly terrain.

Ukraine has in recent years been at the forefront of the effort by some former Soviet republics to switch their alliances to the West, and it appears that the Kremlin has, in some sense, had enough.

President Dmitri A. Medvedev of Russia denounced Ukraine this month for “anti-Russian” policies, citing in particular its “incessant attempts” to harass Russia’s naval base in Sevastopol. Mr. Medvedev condemned Ukraine’s bid for NATO membership and its support for Georgia, and said he would not send an ambassador to Ukraine.

And the criticism has not let up since then.

Monday was Ukrainian independence day, and Russian prosecutors used the occasion to accuse Ukrainian soldiers and members of Ukrainian nationalist groups of fighting alongside Georgia’s military in the war last August. The Ukrainians denied the charges, but they underscored the bitterness in Moscow.

For its part, the Ukrainian government, which took power after the Orange Revolution of 2004, has repeatedly accused Russia of acting as a bully and trying to dominate the former Soviet space both militarily and economically.

Looming is a presidential election in Ukraine in January, which might cause Ukrainian candidates to respond more aggressively to Russia to show their independence. The Kremlin might seek to exploit the situation to help pro-Russian politicians in Kiev.

Both countries publicly avow that they do not want the bad feelings to spiral out of control.

Still, they persist, especially in Sevastopol, where Russia has maintained a naval base since czarist times.

The Kremlin has bristled at what it sees as Ukraine’s disrespectful governing of a city that it formerly controlled — one that was the site of momentous military battles, including in the Crimean War and World War II.

Ukraine appears to regard the base as a sign that Russia still wants to project its military might over the region.

The Ukrainians have not only briefly detained Russian military personnel transporting missiles on several occasions this summer. They also expelled a Russian diplomat who oversees naval issues and barred officers from the F.S.B., the Russian successor to the K.G.B., from working in Sevastopol.

The Ukrainians are trying to close a nearby Russian navigation station and are threatening penalties over supposed pollution from Russian vessels off Sevastopol, which is on the south of the Crimean Peninsula.