Israel has reportedly carried out a pre-emptive strike targeting sites in Iran, according to Israeli media outlet Channel 12. The attack comes amid heightened regional tensions, with Al Jazeera reporting loud explosions in Tehran shortly after the strike. Axios also confirmed that air raid sirens were heard across multiple locations in Israel.

Explosions reported in capital Tehran as Israeli Defence Minister announces "pre-emptive strikes" and announces state of emergency

As the attacks escalate, with fatalities and injuries reported on both sides, Israel issued the stark warning to Iran.

NBC News Chief Foreign Correspondent Richard Engel joins MSNBC's Lawrence O'Donnell to share the latest about what he's learning from his sources in Israel and Iran about the extent of the strikes by Israeli forces across Iran and how the Iranian government is likely to respond.

Iran's Supreme Leader Ayatollah Ali Khamenei speaks during the 36th anniversary of the death of the leader of Iran's 1979 Islamic Revolution, Ayatollah Ruhollah Khomeini, at Khomeini's shrine in southern Tehran,

U.S. stocks opened sharply lower and oil prices jumped after Israel launched airstrikes against Iran. Israel’s defense minister Israel Katz declared a special state of emergency following the attack.