Now that they are in the domestic surveillance game, they have contradictory interests. They were originally intended to jointly ensure the security of U.S. interests while breaking the security of everyone else. So it made sense to advocate improved crypto for, say, U.S. businesses, because that would benefit the U.S. in general by preventing the intelligence agencies of other countries from stealing U.S. corporate secrets.
To take it further, I suppose they want to protect US citizens, companies and government from crypto attacks while using US laws to snoop on them easily. That way, they prevent foreign threats by making it very hard for everyone to break any system in the US. And on the other hand, they can still read everything by issuing subpoenas to any company and ISP they feel like (with borderline constitutional legality in some cases).
