I believed it was “publicly” announced maybe a year or two ago that it was indeed created, sustained and stored.
Anti matter exists ...it has been produced in colliders. HOWEVER, it should be noted that ALL of the anti matter so far produced is so little it has the energy of a matchstick! Thus, NO warheads made of anti-matter. At least not for a very very very very long time ....and if we were even to get sufficient quantities of it, storing the stuff would be something else.