Thousands of Israeli soldiers are being shifted out of the Gaza Strip, the military said Monday, in the first significant drawdown of troops since the war began as forces continued to bear down on the main city in the southern half of the enclave.

The troop movement could signal that fighting is being scaled back in some areas of Gaza, particularly in the northern half where the military has said it is close to assuming operational control. Israel has been under pressure from its chief ally, the United States, to begin to switch to lower-intensity fighting.

Word of the drawdown comes ahead of a visit by Secretary of State Antony Blinken to the region and after the Biden administration bypassed Congress for the second time this month to approve an emergency weapons sale to Israel.

But fierce fighting continued in other areas of Gaza, especially the southern city Khan Younis and central areas of the territory. Israel has pledged to charge ahead until its war aims have been achieved, including dismantling Hamas, which has ruled Gaza for 16 years.

The military said in a statement Monday that five brigades, or several thousand troops, were being taken out of Gaza in the coming weeks for training and rest.

In a briefing Sunday that first announced the troop withdrawal without specifying how many forces were leaving, army spokesman Rear Admiral Daniel Hagari did not say whether the decision meant Israel was launching a new phase of the war.

“The objectives of the war require prolonged fighting, and we are preparing accordingly,” he said.

Israel has vowed to crush Hamas’ military and governing capabilities in its war, which was sparked by the terrorist group’s October 7 attack on southern Israel, which killed more than 1,200 people. Roughly 240 people were taken hostage.

Israel says more than 8,000 militants have been killed. It blames Hamas for the civilian death toll, saying the militants embed within residential areas, including schools and hospitals.

The war has displaced some 85 percent of Gaza’s 2.3 million residents, sending swells of people seeking shelter in Israeli-designated safe areas.

In Khan Younis, where Israel is believed to have thousands of troops, residents reported airstrikes and shelling in the west and center of the city. The military and the militant group Islamic Jihad reported clashes in the area.

The Palestinian Red Crescent said on X, formerly Twitter, that it transported several dead and injured following a strike late Sunday in the Beach Street in Khan Younis. It posted nighttime footage showing medics carrying casualties to ambulances.

Combat was also reported in central Gaza, where Israel expanded its offensive last week.

The military said an airstrike killed Adel Mismah, a regional commander of Hamas’ elite Nukhba forces, in the central city of Deir al-Balah.

Hamas fired a large barrage of rockets toward Israel, including Tel Aviv, as the clock struck midnight on New Year’s Eve.

Israel has said the war will last for months. It has argued that it needs time to clear Gaza of militants’ weapons and infrastructure and to prevent Hamas from being able to stage more attacks. Israel has resisted international calls for a long-term cease-fire, saying doing so would amount to a victory for Hamas.

Shlomo Brom, a retired brigadier general once in charge of strategic planning in the Israeli military, said the troop changes may be a result of the pressure from the Americans. He said it indicated a shift in how Israel was conducting the war in some areas.

“The war is not stopping,” said Mr. Brom. “It is the beginning of a different mode of operation.”

Israelis still largely support the war’s aims, even as the cost in soldiers’ lives is mounting.

Over the weekend, the military said that of the soldiers killed since the ground operation began — as of Monday, 172 in total — 18 were killed by friendly fire while another 11 died by weapons or equipment malfunctions or accidents.