The Pentagon is cherry picking data when it tries to shoot down a popular new movie's portrayal of America's $50 billion nuclear missile defenses ... at least according to national security analyst Joseph Cirincione, who says 'House of Dynamite' has it right!

Check out our chat with Joseph Tuesday on TMZ Live, where he said the government can only declare our anti-ICBM system 100 percent effective if it limits available test results to the last 10 years.

However, he insists the Netflix movie "A House of Dynamite" is far more accurate with the 60 percent success rate in its script.

ICYMI ... the film portrays America's capability of striking down a nuclear attack as a coin toss, which prompted the Pentagon to issue an internal memorandum -- obtained by Bloomberg -- claiming the film is inaccurate, and purely for entertainment purposes.

But, Joseph tells TMZ that's a "dangerous" attitude to have if America's defenses are really just slightly better than 50/50. As he puts it ... you can't base national security on the illusion of safety.

He's not totally ripping the Department of War to shreds ... he notes our technology for short-range rocket interception is spot-on.

"A House of Dynamite" screenwriter Noah Oppenheim has already doubled down on the film's portrayal of U.S. missile defenses ... but it looks like the Pentagon isn't changing its tone anytime soon, either.