Israeli forces have “expanded operations into central Gaza," Israel Defense Forces spokesman Rear Adm. Daniel Hagari said.

In Khan Younis in southern Gaza, the Israelis "are fighting with new methods" and “constantly adjusting our tactics based on the needs of the military operations,” Hagari said.

And in northern Gaza, Israeli forces have "attacked an array of Hezbollah targets in Lebanon," he said.

-ABC News’ Jordana Miller

About 80,000 vials of the measles mumps and rubella vaccine, also called the MMR vaccine, have been delivered to Gaza, according to the United Nations Relief and Works Agency for Palestine Refugees in the Near East.

The MMR vaccine is routinely given to children starting at 12 months old to 15 months old and again at 4 years old to 6 years old.

Israeli Minister for Strategic Affairs Ron Dermer, a key ally of Israeli Prime Minister Benjamin Netanyahu, will meet with Secretary of State Antony Blinken and national security adviser Jake Sullivan at the White House on Tuesday afternoon, according to administration officials.

The meeting will cover "a number of matters related to the conflict in Gaza and the return of hostages held by Hamas," according to National Security Council spokesperson Adrienne Watson.

Dermer was the Israeli ambassador to the U.S. from 2013 to 2021. He now serves in Netanyahu's government and is considered a close adviser to the prime minister.

3:39

Netanyahu vows Israel-Hamas war will 'continue until the end'

Israeli Prime Minister Benjamin Netanyahu says the country is "deepening the war" in Gaza, vowing to fight "until the end.”

-ABC News’ Arthur Jones, Lauren Peller and Jay O'Brien

On Christmas Day, 60 trucks crossed into Gaza via Egypt's Rafah border crossing, and an additional 60 trucks entered Gaza through Israel’s Kerem Shalom crossing, said Wael Abu Omar, the Palestinian spokesman for the Rafah crossing.

On Christmas Eve, the Royal Jordanian Air Force conducted its seventh airdrop of humanitarian aid into Gaza, the U.S. Embassy of Jordan said.