TEHRAN, Iran: Two Iranian paramilitary Revolutionary Guard commanders were killed on April 6 when Israel struck a key petrochemical plant at Iran's massive South Pars natural gas field, potentially challenging a new 45-day ceasefire proposal for Tehran and the United States.

The attack on the gas field was meant to eliminate a major source of revenue for Iran, Israel said. It is also very important for Iran's electricity supply.

However, this strike seemed separate from Donald Trump's threats to attack power plants and bridges if Iran does not reopen the Strait of Hormuz to all ships. Iran's control of this route has pushed up oil prices and disturbed the global economy.

Israel's Defense Minister, Israel Katz, called it a "strong attack on Iran's biggest petrochemical facility." The gas field, shared with Qatar, is the largest in the world and lies under the Persian Gulf. Iranian news agencies said the U.S. and Israel were responsible.

The White House did not immediately respond, but Trump was expected to speak later. After a similar Israeli attack in March, Trump had said Israel would not strike the field again, but warned that if Iran kept attacking Qatar's energy sites, the U.S. would respond very strongly.

Meanwhile, mediators from Egypt, Pakistan, and Turkey have proposed a plan for a 45-day ceasefire and reopening of the strait. The proposal was sent to Iran's foreign minister, Abbas Araghchi, and U.S. envoy Steve Witkoff.

Iran's foreign ministry spokesman, Esmail Baghaei, said messages are being exchanged, but negotiations cannot proceed under threats or pressure. Iranian officials have strongly criticized Trump's warnings, calling them dangerous.

In Islamabad, officials said talks for a ceasefire are progressing, though some groups are spreading misinformation.

At the same time, explosions were heard in Tehran, with jets flying low for hours. Among those killed was Majid Khademi, a senior intelligence officer in Iran's Revolutionary Guard. Israel also said it killed Asghar Bakeri.

Katz said Israel would continue targeting top Iranian officials, saying they are under constant threat.

In response, Kuwait, the United Arab Emirates, and Saudi Arabia activated air defenses to stop Iranian missiles and drones. Iran has also been targeting infrastructure like oil fields in the region.

In Israel, Iranian missiles hit the city of Haifa, where four members of one family were found dead after a residential building was destroyed.