US Defense Secretary Lloyd Austin has ordered a guided missile submarine to the Middle East and is urging the battle group of the aircraft carrier USS Abraham Lincoln to move to the area more quickly, the Defense Department said.

The moves come as the US and other allies are pushing for Israel and Hamas to reach a ceasefire agreement that could help calm growing tensions in the region following the assassinations of Hamas politician Ismail Haniyeh in Tehran and a senior Hezbollah commander in Beirut.

Officials fear retaliation from Iran and Hezbollah for the killings, and the United States is increasing its presence in the region.

Major General Pat Ryder, Pentagon press secretary, said in a statement that Mr Austin spoke with Israeli Defense Minister Yoav Gallant earlier on Sunday and reiterated America’s commitment to “taking all possible steps to defend Israel and noted the strengthening of the strength and capabilities of U.S. forces throughout the Middle East in light of escalating regional tensions.”

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

Last week, Mr Austin said the Lincoln would arrive in the Central Command area by the end of the month.

What his latest order means and how much faster the Lincoln will travel toward the Middle East was unclear on Sunday.

The carrier has F-35 fighter jets on board, in addition to the F/A-18 fighter jets that are also on carriers.

Major General Ryder also did not say how quickly the guided missile submarine USS Georgia would reach the region.

He said Mr Austin and Mr Gallant also discussed Israeli military operations in Gaza and the importance of mitigating harm to civilians.

The call came a day after an Israeli airstrike hit a school converted into an emergency shelter in the Gaza Strip early Saturday morning. According to Palestinian health authorities, at least 80 people were killed and nearly 50 others were injured. It was one of the deadliest attacks in the ten-month war between Israel and Hamas.