US President Donald Trump’s special Mideast envoy Steve Witkoff has told Senate Republicans that if Israel attacks Iran’s nuclear facilities, the Iranian Republic’s response could lead to a mass casualty event.

Axar.az reports, according to Axios, Trump’s envoy told Senate Republicans the US is concerned Israel’s air defenses could be overwhelmed by a retaliatory attack involving hundreds of ballistic missiles.

Iran possesses around 2,000 ballistic missiles, with many capable of carrying heavy warheads. Recent intelligence suggests Iran is increasing production to outpace Israel’s missile defense systems.