ISIS lost its Syrian capital, Raqqa, last week. Trump issued a congratulatory statement; but we've not seen any George W. Bush-style "Mission Accomplished" speeches.

I spoke to Dana White, the top spokeswoman for Defense Secretary James Mattis, about where the U.S. military is at in its fight against ISIS and what challenges lie ahead.

Shrinking caliphate: In Iraq and Syria the Syrian Democratic Forces and the Iraqi Special Forces — with the help of the U.S. military — have retaken an area the size of California. White says that what ISIS still controls "is a territory slightly smaller than New York State."

Most importantly: White points out that "ISIS has not regained an inch of the territory it has lost."

Bottom line: The power of intimidation, to use Mattis' phrase, is working great. But now comes the hard part.

• What White calls "the stabilization piece" — working with Syrians and Iraqis on the ground to ensure ISIS doesn't make a comeback — is going to be incredibly tough and time-consuming work.
• Brett McGurk, the Special Presidential Envoy for the Global Coalition to Defeat ISIS, "is responsible for ensuring the hard fought military gains are maintained — ensuring the 73 coalition members (NATO, Arab League, Interpol and EU) continue to support these communities after the fighting stops."
• "It's why Secretary Mattis and Tillerson work so closely together," White says, "and why [Mattis] insists on having a State Department rep with him when he meets any of his counterparts."