The ‘necessity’ part is usually to do with boots on the ground. Euro-nations are usually reticent on that.
http://m.dw.de/english/mobile.A-17914542-9097.html Excerpt
.... The AFP news agency quoted a Turkish government official as saying that Ankara would not permit a possible US-led coalition to attack IS in Iraq and Syria from its air bases.
"Turkey will not be involved in any armed operation but will entirely concentrate on humanitarian operations," the official told AFP on condition of anonymity.... End excerpt
Have you considered taking your blinders off?