"The Secretary [of Defense Lloyd Austin] believes that we have a robust presence in the Middle East to respond," Kirby said on Tuesday.
Austin is concerned over maintaining the capabilities of US forces overseas in order to deter conflicts and had the "larger geostrategic picture" in mind when he approved the movement of the Nimitz group, he added.
Kirby declined to provide information on the carrier's future presence in the Middle East.
"I do not have announcement on the presence of carriers in that part of the world," he said.
US military officials said earlier that Austin over the weekend ordered the Nimitz to return to the US after an almost eight-month-long trip.
