Western powers like the United States that would like to fight the extremists in Idlib are leery of endangering civilians and have invested heavily in local groups that oppose the jihadists.
The Syrian government and its allies, however, say Idlib is little more than a terrorist haven, where jihadists have imposed their control — a view some American officials share.
“Idlib Province is the largest Al Qaeda safe haven since 9/11,” Brett H. McGurk, the United States envoy to the coalition fighting the Islamic State, said last month. “Idlib now is a huge problem.”
Aid workers and residents say the situation there is more complicated, with a patchwork of groups struggling to provide necessary services to the civilians from all over Syria who have been bused to Idlib to live out the war. Though the extremist groups are militarily strong and the civilians have protested their presence, the militants have not systematically interfered with aid — at least not yet.
“Most people are thinking about the future, and they’re afraid of it,” said Nour Awwad, a media coordinator for Violet Organization, which works in Idlib. “But even if they’re afraid, where can they go?”
Much of Idilb, a poor, mostly rural province along the border with Turkey, joined the uprising against Mr. Assad in 2011, and armed rebel groups and Islamist militias soon formed.
For years, the United States and its allies sent covert aid to rebels, including many in the north, to fight Syrian government forces — a program that President Trump recently ended. Critics have charged that though the aid went to so-called moderate rebels, jihadists also benefited because they fought alongside the rebels and sometimes bought their weapons.