Aboard Air Force One - US President Joe Biden on Thursday hailed Israel's killing of Hamas leader Yahya Sinwar as a "good day" for the world, saying it also removed a key obstacle to a Gaza ceasefire and hostage deal.

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' 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.

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Biden said he would soon be speaking with Netanyahu to "congratulate" him but also to "discuss the pathway" for securing the release of hostages and "ending this war once and for all."

"There is now the opportunity for a 'day after' in Gaza without Hamas in power, and for a political settlement that provides a better future for Israelis and Palestinians alike," added Biden.

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

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.