Smoke and missiles have lit up the skies in Israel and Iran in a fierce standoff triggered by fears over Tehran’s expanding nuclear program. Since June 13, hundreds of military strikes have been exchanged as the two nations remain locked in a conflict that shows no signs of abating.

The State Department raised its travel advisory for Israel to Level 4, the highest level, amid airstrikes from Iran.

The warning came on the fourth day of the conflict, when the Israeli military claimed it had achieved air superiority over the Iranian capital and could fly over the city without facing major threats.