Idlib has become the world’s largest terrorist haven. Most of the nearly 40,000 foreign fighters that flooded Syria during its civil war came through Turkey into northwestern Syria. Today, it is largely controlled by al-Qaeda’s formal affiliate in Syria, which itself is sustained by cross-border trade and enjoys symbiotic relationships with Turkey-backed opposition groups. Now we know the area was hospitable enough for the world’s most-wanted terrorist to camp out with his extended family.

This reality remains a serious threat to U.S. national security; unfortunately, our ability to gain information in these areas will depend not on Turkey but on the other allies we have established in Syria, particularly the Kurdish-led Syrian Democratic Forces (SDF). It was not a surprise to hear President Trump confirm that credible information leading to Baghdadi came from the SDF. This has been the case for nearly all similar operations targeting ISIS leaders in Syria.

The United States helped develop the SDF — a force that grew to 60,000 fighters, including Arabs, Kurds and Christians — as the infantry to defeat the Islamic State caliphate because there were no available alternatives. The United States had sought to build a counter-Islamic State force with the support of Turkey, but two administrations found Turkish-backed forces too riddled with extremists to partner with. The SDF over time suffered 11,000 casualties, and with broad support from the local population, enabled U.S. forces to operate in Syria at small numbers, limited risk and low cost.