A Turkish fighter plane shot down a Russian bomber near the Syria-Turkey border early this morning. Turkey claims the Russian aircraft violated its airspace, while Russia claims it was flying over Syria. Oddly enough, both claims could conceivably be simultaneously true in a sense, but only because Turkey has infringed on Syrian sovereignty by extending its airspace five miles over Syrian territory.

The pilots were able to eject and begin parachuting down, but they were executed in mid-air by gunfire from fighters on the ground. The fighters were insurgents who have been battling the Syrian regime of Bashar al-Assad in a war that has been raging since 2011. A video has emergedshowing insurgents standing over one of the dead Russian pilots.

A Russian helicopter searching for the downed pilots was also shot down, possibly with a U.S.-supplied anti-tank missile.

Turkey is a member of NATO, which means if it enters a war with Russia, it can drag the United States and most of Europe along with it. Such a war could rapidly go nuclear. In October, NATO Secretary-General Jens Stollenberg vowed military support if Turkey went to war with Russia.

Turkey is part of a U.S.-led coalition that has been training, financing, and arming the insurgents trying to overthrow Assad. Syrian regime change is official U.S.policy. That coalition also includes the U.K., France, Saudi Arabia, Qatar, and others. Israel has bombed the Syrian military directly. The insurgency those powers are supporting is dominated by radical Islamist mujahideen militias, including ISIS, Al Nusra (the Syrian branch of Al Qaeda), and others.

The U.S. and several of its allies (including France) have been bombing purported ISIS targets for over a year while continuing to back ISIS’ fellow insurgents.

Recently, Russia began bombing insurgents in Syria in order to save the Assad regime from overthrow, and also in order to weaken or destroy ISIS, Syrian Al Qaeda, and other terrorist threats. Forces from Iran and Iraq, as well as the militia Hezbollah, are also fighting in support of the regime.

Russia has accused the U.S. of not being serious about eliminating ISIS. Russia has also accused Turkey of directly supporting ISIS. The U.S. has long seemed more preoccupied with overthrowing ISIS’s enemy, the secular dictator Assad. And Turkey has seemed more preoccupied with its war against Kurdish militias also fighting ISIS. The U.S., for its part, has accused Russia of being too preoccupied with saving Assad to focus enough on battling ISIS.

All parties in this war have killed many civilians. Members of Syria’s many religious minorities are terrified that if the Assad regime falls, the extremist, theocratic, and intolerant Sunni militias (including ISIS and Syrian Al Qaeda) will perpetrate religious pogroms and mass executions all throughout the country.

For years, the group now known as ISIS was moribund and marginalized. After it crossed over from Iraq into Syria to join the U.S.-sponsored insurgency in 2011, it rapidly grew in strength. In 2014, it returned to Iraq, conquering the north-west of the country down to Baghdad. It joined its Syrian and Iraqi conquests together, declaring a “Caliphate.” A recently disclosed Pentagon intelligence report indicates that U.S. planners anticipated the establishment of such a “Salafist Principality” as a likely outcome of support for the Syrian insurgency.

ISIS has recently launched several terrorist attacks, including bombing a marketplace in Beirut, taking down a Russian airliner, and perpetrating multiple simultaneous attacks in Paris.