How, and whether, to keep atomic time in sync with Earth's rotation is still up for debate. The practice of adding 'leap seconds' to official clocks to keep them in sync with Earth's rotation will be put on hold from 2035, the world's foremost.
The Government Accounting Office (GAO) ] issued a e report examining the challenges the Department of Defense faces in developing and fielding new positioning, navigation and timing (PNT) technologies to complement, augment or replace GPS when it is unavailable. It found that the DOD is not doing enough in this regard.