U.S. President Donald Trump said Monday the International Stabilization Force for Gaza is already running, that more countries would join.

"I think that, in a form, it's already running," Trump said in the Oval Office. "More and more countries are coming into it. They're already in but they'll send any number of troops that I ask them to send."

The Trump-brokered cease-fire for Israel’s two-year war on the Gaza Strip calls for a U.N.-authorized International Stabilization force to help keep peace.

The U.S. Central Command, which oversees U.S. military forces in the Middle East, will host a conference in Doha on December 16 with partner nations to plan the International Stabilization Force for Gaza.

Trump also said his administration was examining whether Israel breached the cease-fire by killing a Hamas leader over the weekend.