their nuclear facilities were destroyed by Israeli's , and they were pretty confident on what they did, US claims were wrong in 2003 .
but coming back to my previous point, if Germans holds up the Europe they did in their first assault, Germany would outmatch America, brits were almost destroyed if not for Reinforcement/Aid from America , but given time to German to consolidate their hold on Europe resources they would easily defeat Americans with their superior Military hardware, and all that which they would've gotten from a defeated British empire, Same thing America did with Nazi scientists , Germans can do with British scientists as well hence they would create a military which would be unmatched by anyone of that time, including US and Japan.