DUBAI, United Arab Emirates (AP) — Israel unleashed airstrikes across Iran for a third day on Sunday and threatened even greater force as some Iranian missiles evaded Israeli air defenses to strike buildings in the heart of the country. Planned talks on Iran’s nuclear program, which could provide an off-ramp, were canceled.

Israel struck at the heart of Iran’s nuclear, missile and military complex early Friday, in an unprecedented attack that reportedly killed three of Iran’s most powerful figures and plunges the wider Middle East into dangerous new territory.

The U.S. says it wasn't involved in the strikes on Iran, but three American officials told NBC News the U.S. is assisting in shooting down Iranian missiles and projectiles targeting Israel.