On Sunday a U.S. F/A-18E took out a Syrian Su-22 after it attacked an area near U.S.-backed fighters, the first such shootdown since America began fighting ISIS there in 2014. Yet Russia, which backs Assad’s Syrian government, has now the United States that it would treat any U.S. coalition planes and drones flying west of the Euphrates River as targets.

According to reports, the U.S. side attempted to warn Russian forces that the Su-22 was bombing coalition forces and that it should stop its attacks. As late as Friday, the U.S. made complaints against Russian fighter jets.

The Su-22 is a Soviet-era attack jet that was widely exported by the USSR, especially to Iraq, Egypt and Syria, as notes. It was used regularly, along with its other variants, at the beginning of Syria’s civil war in 2012. Now, they are being used in airstrikes, dropping unguided munitions and barrel bombs against anti-Assad government forces and civilian populations alike, some of which are backed by Washington. Su-22s fly around 25 sorties per day in Northwest Syria; during several days in late November of 2016, Su-22s flew 34 missions per day.

Along with the Su-24, the Su-22 is the anchor of Syria’s ground attack jet force. Today, it is now down one Su-22.In a statement released on Monday, Russia’s defense ministry demanded an explanation of why it shot down the Syrian Su-22. Moscow also threatened to stop using a key communication channel through which it coordinates military operations with the U.S.—though they may not act on that threat. A U.S. official told the line is still open.

In April, the Russian Foreign Ministry also warned it would suspend the , which allows for both sides to avoid air-to-air collisions by letting the other side know of its location, after the U.S. launched a missile strike on a Syrian airbase, so this is nothing new.

That said, the latest warning from Moscow should not be taken lightly. For one, because President Donald Trump has no clear Russia policy, it is not entirely apparent what steps the White House will take to repel any diplomatic blowback from the latest incident. When Turkey a Russian fighter jet in November of 2015 after it breached its air space, Russia levied against Ankara; the two sides have .

(It also helps that Turkey is a NATO member and Putin likely had no appetite for the consequences of shooting down an alliance fighter jet. For now, Russia’s public response also seems to just be a of .)

But what if the U.S. had shot down a Russian jet this weekend and not a Syrian one? We would be debating a higher stakes game than the one we’re discussing now. But we cannot ignore possible consequences of what will happen if Putin is not bluffing and actually does shoot down a U.S.-coalition plane—especially if it is specifically a U.S. jet. What would Trump do?

So far, the only thing Trump has communicated about Russia this weekend was a imploring the media to stop talking about the Russia investigation.

Putin’s actions, however, go far beyond Twitter. Russia has been battling to expand the Kremlin’s influence in world affairs over the past five years, with Syria being one of its strategic battlegrounds for that purpose.

Scholars and Russia observers have posited many explanations over why Russia wants influence in Syria. One is that Putin wants to counter Western notions of democracy building. This argument falls in line with a report that figures Putin sees his military strategy has succeeded, so it makes sense to finish the job and claim a geopolitical victory. Ultimately, as Julia Ioffe wrote in in 2015, any way Russia can “stick it to the Americans” would assert Moscow “as a leader of world opinion.”

The downing of the Syrian jet may very well have been the right thing to do militarily. It is also doubtful Putin will take it lightly. But, with an Oval Office that spends more time defending itself against collusion allegations with Russia than formulating policy that protects American interests against Russia’s active intelligence agencies, the next major military incident in Syria could force a Russian reaction that the U.S. is in no position to counter. Simply put, if the U.S. is too preoccupied with this Russian collusion mess, it may not be prepared to deal with a conflict with Russia.

And that would mark Trump as the one thing the Republican-lead Congress had long accused Obama of being against Russia: weak. An ironic one, given that a Republican is in the White House and is in, perhaps, an even more compromised position than his predecessor.