President Barack Obama says the problem of cybersecurity hacks targeting the U.S. government is going to accelerate.

Obama is addressing cybersecurity following a massive hack of U.S. government employees' personnel files, described as the most significant cyberattack in U.S. history.

Obama says part of the problem is the U.S. has very old systems for detecting intrusions. He says the U.S. is upgrading old systems agency by agency to ensure that technology is up to date.

But Obama says the problem isn't going away. He says both governments and individuals are "throwing everything they've got" at U.S. systems. Obama says that's why the U.S. must be much more attentive to cybersecurity.

Obama commented Monday in Germany at the close of a summit of the world's leading democracies.