US Defense Secretary Lloyd Austin decided to keep the USS Eisenhower in the US Central Command region for an extended period, in the wake of President Joe Biden's decision to withdraw all US forces from Afghanistan by September.

"And he has approved the addition of some long range bombers to be deployed to the region. Two of those B-52s have arrived in the region," Kirby said.

The Stratofortress bombers are usually based in Qatar, where the US military has an important base.

Kirby did not dismiss the idea that further reinforcements could be sent to ensure the smooth and safe removal of some 2,500 US troops and another 16,000 civilians supporting the US operation in Afghanistan.

There are also another 7,000 NATO troops in the country, who also depend on the United States for material and security support.

"I think it's reasonable to assume, as I've said before, that there could be temporary additional force protection measures and enablers that we would require to make sure that this drawdown goes smoothly and safely for our men and women," Kirby told reporters.