Puzzle of the Day

During a six month period, a number of computer installations were attacked by an intruder who broke in and simply looked at the data on the system. After repeated investigations, it was determined the intruders were from the Netherlands. The Dutch police were asked to investigate, because one of the computers was at a military site, and there was considerable belief that someone was spying against the United States.

After a thorough investigation, the Dutch authorities found that the intruder was a high school student who had no previous record of trouble, and they determined he was not spying; he was simply amusing himself. They declined to proceed any further as (then) attacking computer systems was not a crime under Dutch law.

The intruder continued to break into these systems despite efforts to stop him. While he caused no damage, he tied up lots of the system programmers' time.

What would you suggest they should try to solve the problem? Bear in mind the attacker is under Dutch, and not American, jurisdiction.