The move came amid deep concern over Iran’s response to the killing of senior Hamas and Hezbollah leaders.

US Defense Secretary Lloyd Austin has ordered a guided missile submarine to be sent to the Middle East, and the aircraft carrier battle group USS Abraham Lincoln has also been ordered to move more quickly to the area.

Sunday evening’s order followed a phone call between Austin and Israeli Defense Minister Yoav Galant amid rising tensions following the killing of senior members of Hamas and Iran-backed Hezbollah.

Austin “reiterated the United States’ commitment to taking all possible steps to defend Israel and noted strengthening U.S. military strength and capabilities throughout the Middle East in light of escalating regional tensions,” the Pentagon said in a statement.

The nuclear-powered submarine USS Georgia was already in the Mediterranean in July, according to a social media post by the US military. However, it is rare for the US to publicly announce the deployment of a submarine.

The Abraham Lincoln was in the Asia-Pacific region and had already been ordered to the Middle East to relieve the aircraft carrier battle group of the USS Theodore Roosevelt, which was due to begin its journey home.

Last week, Austin said it was expected to arrive in the region by the end of the month. The carrier carries F-35 and F/A-18 fighter jets.

The US military had already announced that it would send additional fighter jets and warships to the Middle East to strengthen Israel’s defenses against a possible attack by Iran.

Ismail Haniyeh, the political leader of Hamas, the group that controls the Gaza Strip and is backed by Iran, was assassinated in Tehran on July 31. Iran blamed Israel and threatened retaliation. Israel has not claimed responsibility.

Haniyeh was killed the same week that Fuad Shukr, the top military commander of the Iran-backed Hezbollah, was killed in an Israeli raid on Beirut, raising fears that the conflict in Gaza could escalate into a regional war.

The US announcement came a day after an Israeli attack on a school converted into an emergency shelter in the Gaza Strip killed at least 90 people and injured nearly 50, Palestinian health authorities said.

The Pentagon added that Austin and Gallant also discussed “the importance of mitigating harm to civilians, progress in securing a ceasefire, and the release of hostages held in Gaza.”

Nearly 40,000 people have been killed since Israel began its war on Gaza last October after Hamas launched a surprise attack on Israel. An estimated 1,139 people were killed during the attack on Israel and more than 200 people were captured by Hamas.

Washington and other allies have renewed their efforts for a ceasefire.

Hamas said on Sunday that the United States, Qatar and Egypt should present a plan to implement the ceasefire proposal put forward by US President Joe Biden in May, rather than holding “further rounds of negotiations” and discussing new proposals for Gaza.