The U.S. military’s involvement in hurricane relief efforts has “slightly delayed” the deployment of additional American troops to Afghanistan, according to the Pentagon.

“Forces are flowing to Afghanistan, they have been slightly delayed by ongoing hurricane relief efforts,” Lieutenant General Kenneth McKenzie, joint staff director, told reporters, adding:

The [defense] department has been very aggressive in supporting FEMA [U.S. Federal Emergency Management Agency] and the other agencies of the United States government, given the fact that we have a finite number of transport aircraft that will inevitably slow movement to other theaters.

And that — the slight delay in the flow of forces to Afghanistan —  [is] just sort of a natural component of that.

This week, U.S. Defense Secretary James Mattis warned lawmakers that hurricane relief efforts could have an impact on deployments, but did not specifically mention Afghanistan, Reuters reported.

Referring to the American service members assisting in relief efforts to hurricane victims in Puerto Rico, Mattis told the Senate Armed Services Committee:

There is no lack of resources. We are ready to go even to the point that it’s going to impact the deployments, perhaps, of some of these troops overseas next year, because we’ve interrupted their preparation.

The U.S. is expected to deploy an estimated 3,500 additional troops to Afghanistan as part of President Donald Trump’s South Asia strategy, bringing the total number to about 14,000.

Hurricanes Irma and Maria devastated Puerto Rico and the U.S. Virgin Islands, prompting the involvement of the American military in relief activities.

In addition to several naval vessels, there are an estimated 10,000 American troops helping with the relief effort to Puerto Rico, Mattis told lawmakers on Tuesday.

“We have over 10,000 troops there,” he said. “We had two ships pre-positioned. There’s now six ships there.”

Under Trump’s strategy, the U.S. military will intensify its offensive against the Taliban to pressure the jihadists into a reconciliation agreement with the Kabul government that will end the war, noted the secretary of defense.

The Trump administration is planning to ask NATO to contribute an estimated 1,000 additional troops to fight alongside American forces against the resurgent Taliban and other jihadists in Afghanistan.

President Trump, who inherited a chaotic situation in Afghanistan from his predecessor, has decided to base American troop levels in the war-ravaged country on ground conditions, rather than arbitrary timetables.

U.S. military officials have refused to provide a withdrawal date since President Trump unveiled his war strategy in August.

Nevertheless, Afghan President Ashraf Ghani recently told BBC that U.S. troops and their NATO allies would be able to leave Afghanistan “within four years.”