Trump was the first Western leader to stand up and announce that the whole sick business had to stop. All of the nation-builders, responsibility-to-protectors, human rights fanciers and democracy promoters looked with cold blood on the devastation wrought by their blunders.
They had left Syria, Libya, Sudan and Yemen shattered, Iraq in a permanent confessional war, and perhaps a million civilians dead — half a million in Syria since 2011, 300,000 in South Sudan since 2013, 150,000 in Iraq, and about 10,000 each in Yemen and Libya. Trump wants to stop the bloodshed, but humanitarian calculation is not his only motive.
The sectarian war in the Middle East has to stop because it has become a Petri dish breeding jihad from the Caucasus to Southeast Asia. Russia had any number of reasons to step into Syria, but the decisive factor is that thousands of Russian Muslims were fighting there and returning to Russia to wreak mischief.