clipped from online.wsj.com

U.S. and South Korean computer networks were besieged for days by a series of relatively unsophisticated attacks, possibly from North Korea, that were among the broadest and longest-lasting assaults perpetrated on government and commercial Web sites in both countries.

A deeper concern, some cyber-security specialists said, is that the attacks point to weaknesses in defenses erected by the government and corporations that could indicate vulnerability to more-sophisticated attacks in the future on vital functions such as transportation and finance.

South Korean officials are investigating whether the attacks originated in North Korea

U.S. officials noted that the attacks, which appear to have started primarily in South Korea on July 4, coincided with North Korea's latest missile launches and followed a United Nations decision to impose new sanctions.