It is a show of support for key US ally Israel after Iran and the Lebanese Hezbollah group vowed to avenge last month's killings of Hamas political chief Ismail Haniyeh and Hezbollah commander Fuad Shukr.

Austin ordered the aircraft carrier strike group led by the USS Abraham Lincoln, and equipped with F-35 fighters, to "accelerate its transit" to the region, said Pentagon spokesman Major General Pat Ryder.

He said Austin, who spoke with his Israeli counterpart Yoav Gallant on Sunday, had also ordered the USS Georgia guided missile submarine to the area.

Ryder said the pair discussed "the importance of mitigating civilian harm, progress towards securing a ceasefire and the release of hostages held in Gaza," and efforts to deter aggression by Iran-aligned groups in the region.

The United States announced last week that it was deploying the strike group, as well as additional ballistic missile defense-capable cruisers and destroyers, and a fighter squadron.

The Gaza war began with Hamas's October 7 attack on southern Israel which resulted in the deaths of 1,198 people, mostly civilians, according to an AFP tally based on official Israeli figures.

Militants also seized 251 people, 111 of whom are still held captive in Gaza, including 39 the military says are dead.

Israel's retaliatory military offensive in Gaza has killed at least 39,790 people, according to the Palestinian territory's health ministry, which does not provide details on civilian and militant deaths.