Israel will begin pulling thousands of soldiers out of Gaza this week in preparation for a new phase of the conflict, the military announced, though a top official warned that he expected the fighting to continue throughout the year, Report informs via CNN.

The announcement from the Israel Defense Forces marked the biggest known withdrawal of troops from the territory since the war against Hamas began and comes after the military said it was expanding operations in the central and southern Gaza Strip.

A senior US official said Monday that the move shows signs of the country’s gradual shift to a lower-intensity phase of its war.

The 551st and 14th brigades – comprised of reservists – will return to their families and civilian lives this week, the IDF said in a statement.

The 828th brigade, which trains squad commanders; the 261st brigade, which trains army officers; and the 460th brigade, which trains the armored corps, will return to their scheduled training, the IDF said.

The statement said the move is expected to “significantly alleviate economic burdens” and the troops “to gather strength for upcoming activities in the next year, as the fighting will persist, and their services will still be needed.”

In a briefing on Sunday, IDF spokesman Rear Adm. Daniel Hagari said the return of the reservists was aimed at ensuring “planning and preparation for the continuation of 2024… understanding that we will be required for additional tasks and warfare throughout this year.” The objectives of the war “require prolonged fighting,” he added.

The focus of Israel’s ground operation has moved to the center and south of the Strip, but fighting in the north continues, where an estimated 52% to 65% of structures have been damaged and 46,000 housing units completely destroyed, according to the UN.

The IDF extended operations further into Khan Younis in southern Gaza last week. The UN Relief and Works Agency (UNRWA) warned on Thursday that over 150,000 people “have nowhere to go” after the IDF warned residents in many parts of central Gaza that they must urgently leave.

Israel aims to destroy Hamas after the Palestinian militant group’s surprise attacks on October 7 left 1,200 people in Israel dead, according to Israeli authorities, as well as bring back the hostages Hamas captured.

Prime Minister Benjamin Netanyahu said Saturday that Israel’s war in Gaza is at its “highest level and will continue for months,” according to Israel’s Army Radio.

Senior US officials told CNN in early December that they expected the current phase of Israel’s ground operation targeting the southern end of the Strip to last several weeks before it transitions, possibly by January, to a lower-intensity, hyper-localized strategy that narrowly targets specific Hamas militants and leaders.

The US has been pressing Israeli officials to begin the more surgical phase of fighting. The Biden administration has warned Israel that it cannot replicate the kind of devastating tactics it used in the north and must do more to limit civilian casualties.

More than 21,000 people have been killed in the enclave during Israel’s offensive, according to the Hamas-run Ministry of Health in Gaza.

A US official said Monday’s announcement appeared to reflect the start of a gradual shift to lower intensity operations in the north of Gaza that American officials had been encouraging.

The official said the move reflected the success IDF forces have had in Northern Gaza in dismantling Hamas military capabilities. Still, the official cautioned there was still fighting ongoing in the north and that it did not appear to reflect any changes in the south of Gaza.

US officials are viewing the next few weeks as a critical period that will demonstrate Prime Minister Benjamin Netanyahu’s willingness to move to a lower intensity phase of going after Hamas in Gaza.

Later this week, US Secretary of State Antony Blinken is expected to travel to the Middle East to continue discussions with Israeli officials about the next phase of the war in Gaza, which American officials have made clear they expect to begin soon.