U.S. Defense Secretary Lloyd Austin has ordered the deployment of a guided missile submarine to the Middle East, the Pentagon said on Sunday, as the region braces for possible attacks by Iran and its allies after the killing of senior members of Hamas and Hezbollah.

While the USS Georgia, a nuclear-powered submarine, was already in the Mediterranean Sea in July, according to a U.S. military post on social media, it was a rare move to publicly announce the deployment of a submarine.

In a statement after Austin spoke with his Israeli counterpart, the Pentagon said Austin had ordered the Abraham Lincoln strike group to accelerate its deployment to the region.

"Secretary Austin reiterated the United States’ commitment to take every possible step to defend Israel and noted the strengthening of U.S. military force posture and capabilities throughout the Middle East in light of escalating regional tensions," the statement added.

The U.S. military had already said it will deploy additional fighter jets and Navy warships to the Middle East as Washington seeks to bolster Israeli defenses.

Ismail Haniyeh, the political leader of Iran-backed Hamas, was assassinated in the Iranian capital Tehran on July 31, an attack that drew threats of revenge by Iran against Israel, which is fighting the Palestinian Islamist group in Gaza. Iran blamed Israel for the killing. Israel has not claimed responsibility.

The assassination and the killing of the senior military commander of the Iran-backed Lebanese group Hezbollah, Fuad Shukr, by Israel in a strike on Beirut, have fueled concern the conflict in Gaza was turning into a wider Middle East war.

Iran has said the U.S. bears responsibility in the assassination of Haniyeh because of its support for Israel.

Reuters reported several U.S. and coalition personnel were wounded in a drone attack on Friday in Syria, in the second major attack in recent days against U.S. forces amid soaring tensions in the Middle East.