The United States placed the blame for Friday's rapid breakdown in the latest Gaza ceasefire squarely at the door of Hamas, AFP reported.
Speaking after Hamas killed two Israeli soldiers and captured a third, Secretary of State John Kerry said the U.S. “condemns in the strongest possible terms today's attack, which led to the killing of two Israeli soldiers and the apparent abduction of another.”
"It was an outrageous violation of the ceasefire negotiated over the past several days, and of the assurances given to the United States and the United Nations," he added, according to AFP.
Kerry demanded that Hamas "immediately and unconditionally release the missing Israeli soldier."
Earlier on Friday, the White House condemned the Hamas attack as a "barbaric" violation of the 72-hour humanitarian ceasefire which began just hours before.
"The Israelis of course are reporting this morning that that ceasefire was broken," White House spokesman Josh Earnest told CNN. "And that apparently Hamas individuals used the cover of a humanitarian ceasefire to attack Israeli soldiers and even to take one hostage. That would be a rather barbaric violation of the ceasefire."
The White House's Deputy National Security Adviser Tony Blinken called on world leaders to join condemnations of Hamas's actions.
"This is an outrageous action and we look to the rest of the world to join us in condemning it," he told MSNBC television.
Blinken also defended U.S. diplomacy with respect to Gaza, denying that confusion between an Egyptian-led initiative and one from Turkey and Qatar had undermined peace efforts.
"The reason for going through Turkey, going through Qatar, is they have a relationship with Hamas. They need to use their influence with Hamas," he said.
"The Egyptians had an initiative. The Israelis signed up to it repeatedly and that was a good basis for trying to move forward. But Secretary Kerry said last night in announcing this humanitarian pause that it was incredibly fragile and unfortunately we've seen the demonstration that that's true."
Both U.S. officials defended Israel against the charge that its assault on Gaza had been needlessly reckless with civilian lives, while still expressing concern over the death toll.
"Hamas intentionally targets civilians. The Israelis do everything they can to avoid targeting civilians," Blinken said, accusing Hamas of using Palestinians as "in effect human shields."
"Israel holds itself to a very high standard, but what we've seen is that it's incredibly difficult to meet its very own high standard," he added, according to AFP.