Gaza civilians 'centre of gravity' in ongoing war, US defence chief Lloyd Austin says

US Defence Secretary Lloyd Austin on Saturday urged Israel to protect civilians as it bombed Gaza in a bid to target Hamas, saying that shielding noncombatants is necessary for victory in its fight against the group.

Israel's indiscriminate bombing resumed the day before after a week-long truce between Israel and Hamas collapsed, with both sides blaming the other for the breakdown of the deal and the resumption of violence.

Austin told the Reagan National Defense Forum in California that he had "learned a thing or two about urban warfare" while fighting in Iraq and leading the campaign against the Islamic State jihadist group (ISIS).

"Like Hamas, ISIS was deeply embedded in urban areas. And the international coalition against ISIS worked hard to protect civilians and create humanitarian corridors, even during the toughest battles," Austin said.

"The lesson is not that you can win in urban warfare by protecting civilians. The lesson is that you can only win in urban warfare by protecting civilians," he said.

"In this kind of a fight, the center of gravity is the civilian population. And if you drive them into the arms of the enemy, you replace a tactical victory with a strategic defeat."

Israel began its indiscriminate bombing of Gaza with a relentless land and air campaign in Gaza on October 7, which has killed more than 15,000 people.

Israel has also gone on to strike hospitals, refugee camps, schools and other important infrastructure where scores of civilians have sought refuge. Moreover, Israel has imposed a complete siege of the Strip, depriving residents of essentials such as water, food and fuel - consequently worsening the humanitarian situation.

Israeli has also hit targets in Lebanon and Syria, killing scores along the Lebanon-Israel border, including several journalists.

The high death toll in Gaza have provoked widespread anger in the Middle East and provided an impetus for armed groups to carry out attacks against American troops in the region as well as on Israel.

Washington has blamed the attacks on its personnel on Iran-backed forces and responded with air strikes on multiple occasions in recent weeks.

"We will not tolerate attacks on American personnel. And so these attacks must stop," Austin said. "Until they do, we will do what we need to do to protect our troops - and to impose costs on those who attack them."