Spain's Civil Guard said today they had arrested a man who hacked into a US defence department computer, breaching security at a US naval base in California.
The man was part of a group of hackers which attacked more than 100 computer systems, including one at the US Navy's Point Loma base in San Diego where nuclear submarines are maintained in dry docks.
US security services found someone had illegally accessed the computer and subsequently traced the link to Spain.
Spanish authorities pinpointed the group in the southern city of Malaga and arrested one man. Many of the group were students though all were over 18.
"They did it for the challenge, there's no implication of terrorism," a Civil Guard spokesman told Reuters, adding that the man would face unspecified charges.
The Guard did not say when the arrests or the hacking took place.