The Israeli Foreign Ministry is preparing for military conflict with Iran after an incident last week in which Iran allegedly shot down an unmanned U.S. drone. President Donald Trump had planned to retaliate militarily but said he decided against it due to the number of casualties it could cause.

Israeli Foreign Minister Israel Katz said Iran is currently in a "gray zone" of contained confrontation. He said that the Israelis need to be prepared for a "red zone" of more sustained military conflict with the Islamic Republic. 

"We must be prepared for this, and thus the state of Israel continues to devote itself to building military might for the event that it will have to respond to escalation scenarios," Katz said in remarks at the Herzliya Political Conference in Israel.

An Iranian Member of Parliament, Mojtaba Zannour, threatened Israel on Monday saying that "If the U.S. attacks us, only half an hour will remain of Israel's lifespan."

Israel has frequently stuck Iranian-backed military installations in Syria and also targeted Hezbollah, a military organization operating in Syria and Lebanon that is aligned with Iran's government. 

Israel's strikes in Syria have caused controversy. Last year, a Russian military plane was mistakenly shot down over Syria in the aftermath of an Israeli airstrike. 

One of Israel's greatest concerns has been the possibility of Iran acquiring a nuclear weapon. Trump in May 2018 pulled out of the Iran nuclear deal, which reimposed sanctions on Tehran.

Israel's concerns over Iran have prompted warmer relations with Arab Gulf states, according to reports.

Foreign Minister Katz on Sunday visited the United Arab Emirates, where he discussed closer security and intelligence cooperation with the country. The Israel government has also tried to normalize its relationship with Saudi Arabia.