Vice President Kamala Harris, the Democratic presidential nominee in November's US election, added that Israel's killing of the mastermind of the October 7, 2023 attacks was a chance to "finally end the war in Gaza."

The comments reflect growing calls in Washington for a ceasefire even as it backs key ally Israel, amid tensions between Biden and Prime Minister Benjamin Netanyahu over Israel's conduct in the conflict sparked by Hamas's attacks.

"This is a good day for Israel, for the United States, and for the world," Biden, who was traveling to Germany on Air Force One as the news broke, said in a written statement.

Biden said there was now an "opportunity" for peace in the Middle East.

"Yahya Sinwar was an insurmountable obstacle to achieving all of those goals. That obstacle no longer exists. But much work remains before us," he said.

Biden told reporters on arrival that he had called Netanyahu to "congratulate him on getting Sinwar", adding that the Hamas leader "had a lot of blood on his hands."

The US president said he was also dispatching Secretary of State Antony Blinken in the next four or five days to push for a ceasefire.

He said he had told Netanyahu that "now is the time to move on... toward to a ceasefire in Gaza" and that he was now "hopeful" a truce was possible.

Harris has hinted at a tougher approach towards Israel if elected president and called for an end to Palestinian deaths, even as she supports Israel's right to defend itself.

"This moment gives us an opportunity to finally end the war in Gaza," she told reporters after a campaign event in Milwaukee.

"And it must end such that Israel is secure, the hostages are released, the suffering in Gaza ends, and the Palestinian people can realize their right to dignity, security, freedom and self-determination."

The vice president also hailed US special operations and intelligence personnel who "worked closely with their Israeli counterparts to locate and track Sinwar and other Hamas leaders."

Biden's National Security Advisor Jake Sullivan stressed however that US personnel were not involved in the specific operation that killed Sinwar.

"This operation was an IDF operation," Sullivan told reporters traveling with Biden on Air Force One.

Tensions have grown in recent months between Biden and Netanyahu as the Israeli leader seemed to ignore multiple US calls for de-escalation in the Middle East. 

The United States warned Israel on Tuesday that it could withhold some of its billions of dollars in military assistance unless it improves aid delivery to the war-battered Gaza Strip within 30 days.

Washington also said it opposed the way Israel was carrying out mass air strikes on Beirut as it targets Hezbollah -- which like Hamas is backed by Iran -- in Lebanon.

Israel has meanwhile said it will strike back against Iran after a recent ballistic missile attack. Biden has called on it not to strike Iranian nuclear or oil facilities.

But Republican US House Speaker Mike Johnson on Thursday called on Biden to "now work in tandem with Israel to apply a maximum pressure campaign against the head of the snake: Iran."