Kiev, Ukraine ? Russia’s invasion of Georgia has unsettled this former Soviet republic, which like Georgia has applied for membership in NATO but now fears that the U.S. could do little to prevent similar Russian action here.

“If the West swallows the pill and forgives Russia the Georgian war, the invasion of ‘peacekeeping tanks’ into Ukraine will just be a matter of time,” Oleksandr Suchko, the research director of the Kiev-based Institute for Euro-Atlantic Cooperation, wrote on Ukrainska Pravda (Ukrainian Truth), a leading online news site.

Still, not everyone here thinks that Russia would invade Ukraine, which is nearly nine times larger than Georgia, 10 times more populous and much better armed. Many note, moreover, that Ukraine’s president, Viktor Yushchenko, is highly unpopular and isn’t expected to win re-election in 2010.

There are many disputes between the countries, however.

Ukraine has a long-standing issue with the presence of Russia’s Black Sea Fleet at Sevastopol, a holdover from when Ukraine was part of the Soviet Union. Many in Ukraine want the Russians gone in 2017, when the lease agreement expires, but Russia has been suggesting that it intends to stay longer.

Other supposed slights fan tensions.

Many here suspect Russian involvement in the still-unsolved and nearly fatal dioxin poisoning of Yushchenko, who fell ill while he was a presidential candidate in 2004. The Kremlin backed his rival, Viktor Yanukovych, whose path to power was blocked when the democratic Orange Revolution overturned the results of a rigged election.

Even religion is a source of friction in the mainly Orthodox Christian countries. The most recent spat came during last month’s events celebrating the 1,020th anniversary of the conversion from paganism to Christianity of Kyivan Rus, the medieval empire from which the modern nations of Russia, Ukraine and Belarus arose.