Israel took out three of Iran's Russian-made S-300 missile defense systems during last week's retaliatory strike against the Islamic Republic, Fox News has learned. 

Israel carried out the strategic airstrike on Oct. 26, marking a significant escalation in the conflict between the two countries during the operation’s chosen name, "Days of Repentance." The strikes targeted critical military infrastructure, delivering both a symbolic and tactical blow to Iran’s strategic capabilities following Tehran's attack on Israel weeks earlier.

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The Biden administration was informed about Israel's strike in advance. The targets were chosen in an effort to send a pinpoint message to Iran and to degrade its ability to fire ballistic missiles at Israel anytime soon.

At the start of the year, Iran only had four S300 surface-to-air missile systems. In April, Israel took out one of the missile systems in response to Iran's first ballistic missile attack. A senior U.S. official confirmed the airstrikes took out the three S-300 missile systems. 

"The majority of Iran’s air defense was taken out." a senior Israeli official told Fox News. 

On an internal call, President Biden's adviser for the Middle East, Amos Hochstein, said "Iran is essentially naked" with no more missile defense. 

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Israeli warplanes also took out multiple radar systems that are needed to guide the same ballistic missiles that were fired at Israel in April and on Oct. 1 when Iran fired 181 ballistic missiles at the Jewish state. Many of the missiles were destroyed before reaching their target, and others caused minimal damage, the Department of Defense said. 

Removing the radar systems prevents Iran from firing those missiles in the future, a senior official said. 

"Our message is very, very clear… ‘Any threat, anywhere, at any time, we will know how to reach it, we will know how to strike,’" said Israel Defense Forces Chief of the General Staff, LTG Herzi Halevi. 

Halevi emphasized that Israel had only deployed a portion of its capabilities, suggesting that further actions could be taken should Iran escalate.

Defense Secretary Lloyd Austin has urged Iran not to respond to Israel's strikes. 

"We believe that this should be the end of this tit-for-tat," Deputy Pentagon Press Secretary Sabrina Singh said during a meeting today with reporters. "We don't think that Iran should or needs to respond. On Oct. 1, Iran launched the 200 ballistic missiles that were targeting civilian population centers. Israel's response was targeted at military targets."

"We see this as a way to off-ramp," she added. 

Fox News Digital's Efrat Lachter contributed to this report.