For U.S. and allied officials observing the deployment, there was plenty of cause for confusion…and alarm. It’s not just that, more than four years into Syria’s bloody civil war, Russia has decided to jump in and make things more complicated.

No, it’s what kinds of weapons—planes and missiles, especially—Moscow decided to send, and what those weapons say about the Kremlin’s ultimate plan in Syria. Many of them don’t seem to be well-suited to fighting ISIS. They’re built to battle adversaries like the United States…

What’s weird and alarming about the Russian contingent is that it’s not really optimal for attacking lightly armed insurgent fighters. Surface-to-air missiles are only good for destroying enemy aircraft, which Syrian rebels do not possess. And the Su-30s are best suited for tangling with other high-tech forces.

Who in region possesses these high-tech forces? The United States, for one. Israel, too. Why, the United States, of course. Russia’s warplanes and missiles in Syria could pose a threat to America’s own aircraft flying over the country—all in order to carve out and preserve a portion of Syria that the United States can’t touch.