To politicians, leader writers and rent-a-gobs I would say just take a step back and look at the events of the past decade with some perspective. And please re-read your history of the 30 years war in Europe. Then it was broadly a fight between two Christian factions, Catholics and Protestants, but with alliances of convenience that saw Catholics fighting with Protestant forces and vice versa, nobility fighting with the armed bishops and every petty lord out to land-grab, rape, pillage and spoil. The long drawn-out fight, with scores of small gains and losses, changes of prominence, as fluid as mercury, petered out only when there were too few left alive to fight and too little food to preserve even the survivors.
The centuries-old conflict between Shia and Sunni Moslems has broken out into factional war across the globe, wherever they are gathered. Yes, even in the UK - where Douglas Murray has noted attacks on Shia mosques by Sunni Islamists. Behind the fanatical and primitive Sunnis are the powerful oil states led by the corrupt and despotic hereditary tyranny of Saudi Arabia; leading the Shia are the zealots of Persia. One side throws queers from high buildings, the other hangs them from construction cranes. In terms of savagery and barbarism there's really not a lot to choose between them. The old Sykes-Picot nations of the middle east mostly contain mixes of Shia and Sunni with other tribal or ethnic allegiances; Kurds are Kurdish first, Moslem second.
For anyone naive enough to think that the migrant problem will end if we just sort Syria out, forget it. The fighting will just spring up elsewhere and produce a new stream of migrants. Two things are needed to halt the tsunami of migrants at source; the prospect of prosperity at home (butter not guns) and a quiescence to the civil war. Until the civil war draws to a close, we will always be under pressure from migrants fleeing its effects.
Nuking Mecca and Medina would probably be more effective in ending the flood of migrants than anything else - and if we're not prepared to do that, we need to shut the gates and let them fight it out. We haven't shed tears for the thousands of three and four year-olds slaughtered in Iraq since 2003 by car bombs, suicide bombers and gang-bangers; perhaps the press photos of their remains, generally a few small body parts and large smears of blood and viscera, didn't make it to the front page.