The United States has gathered evidence indicating that key Iranian leaders were taken aback by the unprecedented strikes on Israel by the Palestinian Islamist group Hamas, according to the New York Times, citing American officials.

The White House did not reply quickly to a request for comment.

White House national security adviser Jake Sullivan said on Tuesday that the U.S. did not have confirmation of an Iranian link to the attack.

“We are talking to our Israeli counterparts on a daily basis about this question. We are looking back through our intelligence holdings to see if we have any further information on that,” he said.

Hamas, an Iranian-backed group, launched a surprise attack on Israel on Saturday, killing hundreds of Israelis and seizing dozens of hostages. Israel’s death toll rose to 1,200 with over 2,700 wounded, its military said, from the militants’ hours-long rampage after breaching the border fence enclosing Gaza on Saturday.

Israel subsequently battered Palestinians with air strikes in Gaza. The retaliatory strikes on the blockaded enclave have killed 1,055 people and wounded 5,184, Palestinian officials say. The U.N. said nine staffers working for the Palestinian refugee agency were among the dead.