Iran has targeted only military sites in Israel, not civilian sites, a source identified as being with the Israeli military told ABC News Saturday afternoon.

Meanwhile, the Israel Defense Forces have moved up the arrival estimate for the drones, numbering potentially anywhere from 400 to 500 missiles launched at Israel mainly from Iran, but from other allied locations in Iraq, Syria, southern Lebanon, and the Houthis. The unmanned suicide drones are said to be the same that have been used in Ukraine.

The strikes were ordered late Saturday in retaliation by Iran for a strike last week in Damascus that took out several senior Iranian military leaders, including Islamic Revolutionary Guard Corps Brig. Gen. Mohammad Reza Zahedi.

Tehran holds Israel responsible for the April attack on the Iranian consulate in Damascus, and the U.S. military believes Israel carried out the attack. Israel has made no comment on it.

Biden administration officials this past week also told NBC News that the retaliation inside Israel is likely to focus on hitting military or intelligence targets.

Saturday, a senior Biden administration official warned on NBC that Iran's assault will involve dozens of cruise and ballistic missiles and that the administration expects Israeli government facilities to be targeted, but not civilian or religious sites.

U.S. assets in the region are also not expected to be targeted, the official commented.

The U.S. and Israel have been coordinating defense moves, the official added, saying "We're ready. The Israelis are ready."

Information from The Associated Press was used in this report.

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