RAFAH, Gaza Strip — Israel and the United States showed their sharpest public disagreement yet over the conduct and future of the war against Hamas terrorists as the two allies became increasingly isolated by global calls for a cease-fire.

The dispute emerged Tuesday while Israeli forces carried out strikes across Gaza.

President Biden said he told Prime Minister Benjamin Netanyahu that Israel was losing international support because of its “indiscriminate bombing” and that Netanyahu should change his government, which is dominated by hard-right parties.

Biden’s comments came as the White House national security adviser heads to Israel this week to discuss with Netanyahu a timetable for the war — and what happens if Hamas is defeated.

Defense Secretary Lloyd Austin will travel to Israel next week for a visit the Pentagon said aims to show U.S. support for Israel but also to press the need to avoid more civilian casualties in Gaza.

The U.S. has urged Israel to do more to reduce civilian casualties since it launched its invasion of southern Gaza at the beginning of the month.

Fierce clashes raged Tuesday in Gaza City’s Zaytoun and Shijaiya neighborhoods, as well as in Jabaliya, a densely built urban refugee camp, residents said.

Israel also has begun flooding some Hamas tunnels, a U.S. official confirmed, speaking on condition of anonymity because they were not authorized to discuss the action. Israelis said they are testing the targeted flooding of tunnels on a limited basis and are exploring the idea as one of a range of options to degrade the tunnel network, according to another U.S. official familiar with the matter.

Biden said during a news conference with Ukrainian President Volodymyr Zelenskyy that there were assertions that no hostages were in Gaza tunnels being flooded with seawater by the Israelis, but “I don’t know that for a fact.”