U.S. forces shot down a Syrian jet yesterday, which prompted  a threat from Russia:
Russian officials on Monday threatened that their country would treat U.S.-led coalition planes in some parts of Syria as targets after the U.S. military shot down a Syrian Air Force jet on Sunday.
Russia’s defense ministry said planes flying in Syria, west of the Euphrates River, would be considered targets.
U.S. support for rebels in Syria was always likely to lead to clashes with the Syrian government and its patrons sooner or later. That is why it was an irresponsible and dangerous policy from the beginning. U.S. officials have talked about defending proxies against attack from the regime for years, but in the last few months this foolish position has been put to the test. It is possible that Russia might not use its air defenses against coalition planes in Syria, but there is now reason to fear that they might. Russia is also once again suspending the “de-confliction” process that has reduced the chances of accidents and collisions between Russian and U.S. forces. The risks to U.S. and allied pilots have just increased substantially, and the tacit permission that our planes have been given to operate against ISIS has evidently just been withdrawn. Through a mixture of foolish continuation of meddling in Syria and mindless increases of U.S. support for Syrian rebels, the Trump administration has carelessly created the conditions for escalation into a larger conflict with the Syrian government and its patrons, including Russia.
No one in Washington will care, but it is worth remembering that the U.S. has no authority to be engaged in hostilities anywhere in Syria, and our government certainly has no authority to attack Syrian government forces operating inside their own country in support for anti-regime insurgents. Obama had no right to expand the war on ISIS into Syria, and Trump has no right to involve us in a war with the Syrian government. Our Syria policy is unwise and divorced from U.S. security interests, and it is also illegal.