Israel's attacks on Iranian targets can be expected for days or potentially weeks, as the goal is to destroy Iran's missile arsenal and nuclear capability, an unnamed Israeli Defense Forces official said Friday.

The official told ABC News Friday that Israel now has full control over Iran's skies after destroying its air defenses during two attacks last year.

Further, Iran has launched drones, not missiles, in response to Israel's deadly strikes Thursday because Israel also destroyed all missiles that were ready to launch.

Iran has deployed hundreds of drones toward Israel, but they were intercepted, the source said.

Meanwhile, the official told ABC News that an estimated 200 Israeli jets flew in a 2,000-mile round-trip crossing other hostile nations such as Syria and Iraq, but there were no mishaps or casualties during their trip.

Iran on Friday said Israel declared war with its wave of strikes, which hit about 100 targets and killed several senior military figures and top nuclear scientists Thursday and as attacks continued into Friday.

Iranian Foreign Minister Abbas Araghchi, in a letter to the United Nations, described Israel's attack as a "declaration of war" and called on the Security Council to "immediately address this issue."

Iran's supreme leader, Ayatollah Ali Khamenei, warned there will be a "bitter and painful" fate for Israel with the attacks, and the Iranian military said there are "no limits" to the response.