Two recent tragedies — the downing of a Russian civilian airliner over the Sinai Peninsula and the terrorist massacre in Paris two weeks later — seemed to give Russia and the West something to agree upon: the Islamic State (IS) militant group must go. But a closer look at Russia's military operations in Syria — not to mention Turkey's downing of a Russian warplane — suggests that it would be premature to conclude that Russian and Western objectives can be brought into alignment.

Of course, Russia claims that its Syrian intervention is aimed at defeating the Islamic State and "other terrorists." But, according to the U.S. State Department, more than 90 percent of Russian airstrikes so far have been directed not at IS or the al-Qaida-affiliated Jabhat al-Nusra, but at the armed groups that are fighting both IS and Russia's ally, Syrian President Bashar Assad. In fact, IS has made advances in Aleppo since the airstrikes began.

This is not to say that annihilating IS is not on Russian President Vladimir Putin's agenda. It almost certainly is. But he also has other objectives: to protect Assad's regime, to expand Russia's military presence and political influence in the eastern Mediterranean and the Middle East, and perhaps even to push up the price of oil.