The Israeli military is gearing up together with U.S. forces for a major missile defense exercise, the IDF announced Thursday.

The Associated Press reported that the “Austere Challenge 12” drill is designed to improve defense systems and cooperation between the U.S. and Israeli forces.

While the drill follows a ten-day Iranian naval exercise near the Strait of Hormuz, the IDF told AP the drill with the U.S. was planned long ago and is not tied to recent events.

Israeli and U.S. officials told AP the exercise would be the largest-ever joint drill by the two countries.

A few weeks ago, the Commander of the Third Air Force of the U.S Military, Lt. Gen. Frank Gorenc, arrived in Israel to prepare for the joint training exercise.

A spokesman for the IDF did not give a date for the drill Thursday, but a senior military official told AP it would be in the next few weeks, adding it would be the biggest missile defense drill ever held.

The Israeli official said thousands of American and Israeli soldiers from different units would take part. He said the drill would test multiple Israeli and U.S. air defense systems against incoming missiles and rockets.

The Islamic Republic followed its threat to close the Strait of Hormuz with another earlier this week, when Iranian army chief Ayatollah Salehi warned USS carrier John C Stennis not to return to the Persian Gulf after having left the area through the Straits of Hormuz in a “pre-planned, routine operation.”

The U.S. responded to the Iranian threat with a calm statement read by Pentagon spokesman George Little and which warned Iran, “The deployment of U.S. military assets in the Persian Gulf region will continue as it has for decades.”

On Wednesday, the IDF staged a surprise drill at its base at the port of Haifa as Iran completed its drill.

Haifa base commander Brigadier General Eli Sharvit, ordered the surprise drill to check the readiness of Israel Navy vessels to depart from port and head out to sea to conduct operation, the IDF said. A majority of the Israel Navy’s operational strength is based in Haifa, which was bombed several times by Hizbullah terrorists in the Second Lebanon War in the summer of 2006.

Meanwhile, Martin Van Creveld, a military historian at the Hebrew University of Jerusalem, estimated on Thursday that the joint Israel-U.S. drill was intended not only to practice military maneuvers but also to pressure Iran.

“Defending against an attack is not something that you improvise from today to tomorrow,” Van Creveld told AP. “It’s something you have to prepare, you have to rehearse, you have to prepare for. This, among other things, is an exercise to show Iran, the people in Tehran, that Israel and the United States are ready to counterattack.”