AES(Rijndael) was the weakest out of the final three contenders for the advanced encryption standard. Serpent and Twofish were clearly more secure but Rijndael

AES(Rijndael) was the weakest out of the final three contenders for the advanced encryption standard. Serpent and Twofish were clearly more secure but Rijndael was chosen because of its speed. There are attacks that have broken 11 of out the 14 AES-256 rounds (https://www.schneier.com/blog/archives/2009/07/another_new_aes.html https://www.schneier.com/blog/archives/2009/07/another_new_a...). Using a combination of RNG weaknesses, CPU attacks, software vulnerabilities I don't think its crazy to conclude that the FBI can "crack" AES implementations in targeted investigations.