Trump hints at 'action' if Hamas doesn't return hostage bodies

President Donald Trump, Egyptian President Abdel Fattah El-Sisi, Turkish President Recep Tayyip Erdoğan and Qatari Emir Tamim bin Hamad Al Thani formally signed the Gaza ceasefire agreement at a ceremony in Egypt on Monday as other world leaders looked on.

“This took 3,000 years to get to this point. Can you believe it? And it's going to hold up too. It's going to hold up,” Trump said.

Before signing the agreement, Trump praised “the richest in the world” gathered around him, saying they “really care for their countries” and credited them for joining forces “to get Gaza straightened out.”

“Why this happened is they all came together and they wanted to get Gaza straightened out. They wanted to get the whole thing straightened out,” Trump said. “It got to a point where it was just crazy. And once they got together and once we started talking, it went really, to me, it went smoothly. It went so smoothly. It was such a big help. But it went so smoothly that nobody could even believe it that we're sitting here and getting this all certified out and all done, and everybody’s happy about it.”

-ABC News' Fritz Farrow

Five of the 20 living hostages who returned to Israel on Monday are being treated at Beilinson Hospital, part of Rabin Medical Center in Israel.

The five hostages -- Evyatar David, Guy Gilboa-Dalal, Alon Ohel, Eitan Mor and Avinatan Or -- are undergoing “comprehensive medical evaluations,” hospital director Dr. Lena Koren said in a statement.

“For each of them, we have assembled a dedicated and personalized medical team, including a physician, mental health professionals, a physiotherapist, and a dietitian," Koren said.

-ABC News Jordana Miller

Avinatan Or, one of the last 20 living hostages released from Gaza on Monday, has reunited with his girlfriend, former hostage Noa Argamani. Or was seen kissing a beaming Argamani on her cheek in a newly released photo.

Or and Argamani were both kidnapped at the Nova music festival on Oct. 7, 2023, and were immediately separated. Argamani was rescued from Gaza last year.

President Donald Trump is greeting world leaders at a peace summit in Sharm el-Sheikh, Egypt, that's marking the first phase of the ceasefire agreement.

According to a source in the Egyptian president’s office, attendees of the summit include: the king of Jordan, the emir of Qatar, the emir of Kuwait, the Saudi foreign minister, Palestinian President Mahmoud Abbas, the vice president of the United Arab Emirates, the secretary-general of the United Nations, the chancellor of Germany, former United Kingdom Prime Minister Tony Blair and the prime ministers of the U.K., Italy, Spain, Pakistan, Canada, Iraq and Norway.

Israeli Prime Minister Benjamin Netanyahu was invited but is not at the summit. He said he could not attend because Monday night to Wednesday night marks the holidays of Shemini Atzeret and Simchat Torah.