US Defense Secretary Lloyd Austin on Saturday called on Israel, which has resumed its shelling of the Gaza Strip, to protect Palestinian civilians, which he said is a prerequisite for a victory on the ground against Hamas.

The former general, who fought mainly in Iraq and Afghanistan and led the fight against the Islamic State group, explained that he saved “a thing or two for fighting inside cities”, during a speech at his National Defense Forum Reagan Institute, California.

“The lesson to be learned is not that one is assured of victory in a war in the urban fabric if one protects civilians. The lesson is that one cannot win a war in the city unless one protects civilians,” he stressed.

“In this kind of battle, the center of gravity is the civilian population. And if you push them into the arms of the enemy, you replace a tactical victory with a strategic defeat,” he added, believing that “like Hamas, the Islamic State was deeply rooted in urban areas”.

The Pentagon chief’s speech came a day after fighting resumed between Israel and Hamas, where the Israeli military resumed its shelling of the Gaza Strip after a seven-day ceasefire.

Israel and Hamas blame each other for ending the truce, which allowed the release of about a hundred hostages in exchange for the release of 240 Palestinians.

The war erupted after the Palestinian Islamist movement’s unprecedented attack on Israel on October 7, which left 1,200 dead, mostly civilians, according to authorities.

In retaliation, Israel launched devastating bombardments against Palestinian territory, and on October 27 began a ground offensive.

The Israeli strikes — which the Hamas government says have killed more than 15,000 people, including more than 6,150 under the age of 18 — have fueled anger against Israel in many Middle Eastern countries and armed groups have carried out attacks against Israel and US troops in the region.

US forces in Iraq and Syria in particular have been the target of a series of attacks in which nearly sixty Americans have been injured.

Washington blamed Iran-linked groups and responded with airstrikes.

“We do not tolerate any attack against American personnel,” assured Lloyd Austin. “As long as they continue, we will do whatever is necessary to protect our troops and make those who attack pay the price,” he warned.