Sunak borrowed a phrase associated with British wartime leader Winston Churchill, pledging to stand by Israel "in its darkest hour" following the October 07 rampage by Hamas gunmen who killed 1,400 Israelis.
Israel has responded to the deadliest attack in its 75-year history by vowing to annihilate Hamas, putting the entire Gaza Strip's 2.3 million people under a total siege, and bombarding the enclave in strikes that have killed thousands and made more than a million homeless.
Western countries have tried to balance their support for Israel with calls to ease the plight of Gazans, but Sunak's emphasis was firmly on the former.
"Above all, I'm here to express my solidarity with the Israeli people. You have suffered an unspeakable, horrific act of terrorism and I want you to know that the United Kingdom and I stand with you," Sunak told reporters after landing in Tel Aviv hours after Biden left.
Later appearing beside Prime Minister Benjamin Netanyahu, he said, "We will stand with you in solidarity. We will stand with your people. And we also want you to win."
