The F-35A comes standard with a receptacle for flying boom refueling
HOWEVER Lockheed also designed the F-35A to accommodate a probe and drogue system. This was necessary as the large majority of allied air forces do not use the flying boom.
http://www.dodbuzz.com/2012/06/19/lockh ... -the-f-35/Steve O’Bryan - vice president for F-35 business development Steve O’Bryan - vice president for F-35 business development:
“We anticipated a number of the operators would want probe-and-drogue refueling in the F-35A and we kept that space empty on the F-35A to accommodate probe and drogue refueling. We‘ve done a number of studies – funded studies, not projects – funded studies to evaluate that, paid for by the countries who want that to happen. It’s a relatively easy … doable change.”
If we don't order them with the probe and drogue system, it's our own damn fault. It is an option.