While the threat of Israeli airstrikes has loomed for decades, only some of the sites have been built underground.

The military exchanges worsened between Israel and Iran overnight on Monday as strikes hit residential areas, killing and wounding civilians on both sides.

Israel and Iran have traded more missile attacks despite international calls for a halt to the fighting, with neither country showing signs of backing down as the conflict between the regional foes raged for a third day.

Israel faced retaliation from Iran after launching missiles against Tehran's leadership and energy infrastructure as part of "Operation Rising Lion" this weekend. Iran's military responded with a wave of missile strikes against Israel,

Smoke and flames filled the sky over Tehran as Israel struck oil and gas facilities in the Iranian capital and targeted more nuclear facilities during attacks that carried on into Sunday after starting two days earlier.

The decision comes as officials say they believe that Israel is preparing to launch a military attack on Iran. Tehran condemned the vote.

Experts suggest the U.S. has a strategic opportunity to leverage Iran's weakened position for a nuclear deal after Israel's targeted strikes on Iranian nuclear and military sites.

Iran has warned it will ramp up its nuclear activities after the United Nations nuclear watchdog’s 35-member board of governors adopted a resolution Thursday declaring it in breach of its non-proliferation obligations.