Once the United States has a backdoor key, every other nation will demand one as well, and there won't be any grounds to refuse. Which creates two problems: -

Once the United States has a backdoor key, every other nation will demand one as well, and there won't be any grounds to refuse. Which creates two problems: - Obviously you can't reuse the same master key, so now you need 180+ keys, meaning 180+ backdoors into the system. It is ridiculous to expect that all of these will remain secure; the United States can't even secure the OPM database so even ours will probably be leaked, and countries with more bribe-prone law enforced will give it up even faster, and now everyone is pwned. - Law enforcement are frequently the bad guys. YMMV on how often this is the case in the United States but it's certainly inarguably the case in many places abroad. Mandatory backdoors means no possibility for secure communications about dissidents and "inconvenients" in those countries.