"Well, the one thing I can say is that there were no U.S. forces, no U.S. boots on the ground involved in this operation. We did not participate militarily in this operation," US National Security advisor Jake Sullivan said in a CNN interview on Sunday. There have been widespread claims that US special forces advisers were on the ground in some capacity, but this hasn't been met with confirmation.

However, it has been reported that "A U.S. official told Axios the U.S. hostage cell in Israel supported the effort to rescue the four hostages." The precise level of 'support' and details of this involvement hasn't been revealed, but The New York Times has so far described that US officials in Israel had been "providing intelligence and other logistical support."

Despite the freeing of the four hostages being a clearly big 'win' and victory for Israel, which the White House also congratulated, it quickly emerged that the refugee camp at Nuseirat suffered a massacre during the operation.

The Palestinian side is saying that at least 274 people were killed, mostly civilians, in the large-scale attacks which reportedly paved the way for the elite counterterror team to go in and rescue the captives while under heavy fire. Israel launched significant strikes on the surrounding area to protect the Israeli elite hostage rescue team.

Sullivan confirmed during the same CNN interview that "innocent people were killed" in the Israeli military operation to free the group of hostages. He didn't say how many civilian casualties there were, however. "We, the United States, are not in a position today to make a definitive statement about that. The Israeli defense forces have put out one number. The Hamas-run Gaza Health Ministry has put out another number," Sullivan said.