Story highlights Defense Secretary James Mattis spoke about the challenge publicly for the first time Tuesday

The impact is already being felt on troop deployments to Afghanistan

(CNN) The extended deployment of military cargo jets and Navy ships to help with Hurricane Maria and Hurricane Irma relief efforts is causing military planners to scramble and recalculate future deployments all the way from Afghanistan to the Korean Peninsula, according to several defense officials familiar with discussions underway inside the Defense Department.

Due to security concerns, officials refused to discuss specific changes in deployment timelines or the units involved, but sketched out how they could impact overseas deployments into 2018.

Defense Secretary James Mattis spoke about the challenge publicly for the first time Tuesday, testifying before the Senate Armed Services Committee that the military will stay in Puerto Rico as long as needed: "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 impact is already being felt on troop deployments to Afghanistan. Planners are considering several solutions including delays for troops scheduled to deploy, either as part of the additional 3,500 troops being sent, or to replace existing forces.

Forces scheduled to come home may not be able to leave Afghanistan until their replacements arrive, and some departing troops may have to leave equipment behind until aircraft can be sent to pick it up.

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