The U.S. says it has indications Iran is planning to “imminently” launch a ballistic missile attack against Israel in the latest escalation between the two countries, a senior White House official told Global News.

“We are actively supporting defensive preparations to defend Israel against this attack. A direct military attack from Iran against Israel will carry severe consequences for Iran,” the official wrote.

Amid the threat, the U.S. embassy in Jerusalem has directed all government employees and family members to shelter in place until further notice. The last time such an order was issued was ahead of Iran’s missile barrage in April.

That attack was the first time Iran had launched a direct attack on Israel, though few reached their targets. Many were shot down while others appeared to fail at launch or crashed while in flight.

In a statement on Tuesday, Israeli Prime Minister Benjamin Netanyahu said Israel was facing “large challenges” as it fights an Iranian axis. He urged the public to listen to public safety guidelines from the military’s Home Front Command, but did not make direct mention of the missile threat.

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U.S. ships and aircraft are already positioned in the region to assist Israel in the event of an attack from Iran. There are three U.S. Navy destroyers in the Mediterranean Sea, an aircraft carrier in the Gulf of Oman and fighter jets arrayed throughout the region. All have the abilities to shoot down incoming missiles.

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The potential threat from Iran comes a day after the Israeli military began what they called limited, localized and targeted raids against Iran-backed Hezbollah in the border area of southern Lebanon.

That day, Netanyahu warned Iran that there was “nowhere we will not go to protect our people and protect our country,” accusing the Iranian government of plunging the Middle East “deeper into war” at the expense of its own people.

It also follows the assassination of Hassan Nasrallah – the most powerful leader in Tehran’s “Axis of Resistance” against Israel and U.S. interests in the Middle East — one of the heaviest blows in decades to both Hezbollah and Iran, and followed two weeks of intensive airstrikes.

Nasrallah’s killing, along with the assassinations and systematic attacks on the group’s communications devices, constitute the biggest blow to the Shi’ite movement since Iran created it in 1982 to fight Israel.

with files from Global News’ Reggie Cecchini and The Associated Press