Israel has vowed to keep fighting in Gaza until it crushes Hamas after one of the deadliest single battles of the war for its soldiers, even as it faces mounting international calls for a cease-fire and unease on the part of its closest ally, the US.

The ambush is a fresh reminder that Hamas is still able to fight after six weeks of devastating warfare aimed at crushing its military capabilities. Israel has imposed a total siege and flattened much of northern Gaza with a massive air and ground campaign, driving hundreds of thousands of people from their homes.