Secretary of State Mike Pompeo said Tuesday that the Islamic State remains a “complicated” foreign policy challenge and is actually stronger in some corners of the world today than it was before having its self-proclaimed “caliphate” decimated by U.S.-backed forces in Syria and Iraq. “There are certainly places where ISIS is more powerful today than they were three or four years ago,” said Mr. Pompeo, who asserted that President Trump “is very focused on making sure that we apply the right resources against the problem.” Mr. Pompeo’s rare acknowledgment of the Islamic State’s threat, a group President Trump has claimed...