Anonymous hackers claim to have launched another attack. This time they've targeted the North Atlantic Treaty Organization (NATO).

Hi NATO. Yes we haz more of your delicious data. You wonder where from? No hints, your turn. You call it war; we laugh at your battleships, wrote the hackers from their Twitter account, @AnonymousIRC.

The hackers say they have stolen an entire gigabyte of information from NATO.

The FBI arrested some 21 alleged hackers were arrested this week, according to the LA Times. Arresting people won't stop us, FBI. We will only cease fire when you all wear shoes on your heads. That's the only way this is ending, wrote @LulzSec.

@AnonymousIRC posted the same message to its Twitter feed. It appears the two groups have banded together.

@LulzSec is a hacking group targeted by the FBI that has since regrouped.

But who is @AnonymousIRC?

It is unclear why they are attacking NATO, but this is what we know:

@AnonymousIRC wrote on its twitter page: We are Anonymous. We are #AntiSec we are Legion. We do not forgive. We do not forget. We love you. Expect us.

A little cryptic, perhaps.

#AntiSec refers to the Anti Security Movement, and is also written as anti-sec.

The Anti Security Movement opposes the computer security industry.

They are against the disclosure of private information, but believe that the computer security market uses an array of scare tactics to force people into buying their software.

Members of the anti-sec group call themselves hacktivists.

So, we are working (and) the FBI are working. Let's see who is more efficient, @AnonymousIRC wrote.