Ten years to the day after the formal launch of the US-led operation against the Islamic State, the US and its Nato allies gathered in Brussels on Thursday to discuss the future of a mission facing increasing headwinds.Niger kicked out the US military from its counter-terrorism base in West Africa this summer. Afghanistan has been largely off-limits since the Taliban’s 2021 takeover. Iraq wants the Pentagon to start reducing its personnel and end coalition operations there. At the same time, US officials warned the global threat from Islamic State is growing in Africa and elsewhere,…