WASHINGTON (NewsNation) — President Joe Biden said Friday he expected Iran to launch a strike on Israel “sooner rather than later” and vowed the U.S. would help defend Israel if such an attack were to happen.

Asked what his message to Iran was, Biden delivered a stark one-word warning: “Don’t.”

“We are devoted to the defense of Israel. We will support Israel, we will help defend Israel,” the president said. “Iran will not succeed.”

Tehran has signaled a calibrated retaliation against Israel for the airstrike on its consulate in Damascus, Syria, on April 1 that killed several top military commanders. Iran’s supreme leader, Ayatollah Ali Khamenei, said Israel must be punished for the attack.

“When the Zionist regime attacks an Iranian consulate in Syria, it is as if it has attacked Iranian soil. That malicious regime has made a wrong move. It should be punished, and it will be punished,” Khamenei wrote on X Wednesday.

Amid intelligence on impending attacks, the Defense Department started moving additional assets to the Middle East region to “bolster regional deterrence efforts and increase force protection for U.S. forces,” a defense official tells NewsNation.

The U.S. has approximately 40,000 military personnel deployed throughout the Middle East.

Secretary of Defense Lloyd Austin spoke to his Israeli counterpart, Yoav Gallant, to reiterate the ironclad U.S. support for Israel’s defense amid growing threats from Iran and its proxies.

“Secretary Austin assured Minister Gallant that Israel could count on full U.S. support to defend Israel against Iranian attacks,” Pentagon press secretary Maj. Gen Pat Ryder said in a statement Thursday.