According to news reports, South Korean government web sites have been hit by a large distributed denial of service (DDoS) attack which has made several of them inaccessible. A number of large South Korean bank web sites have also been attacked.
This follows AP news reported last night that US government web sites were attacked beginning on the 4th of July, a major US holiday. At least 14 major web sites were attacked; the Department of the Treasury, Secret Service, Federal Trade Commission, Department of State, Department of Homeland Security, Department of Defense, Federal Aviation Administration, Department of Transportation and White House web sites were all said to have been affected to some degree. The DOT web site was reportedly brought down for 2 days, for example, and some of the others continue to suffer sporadic outages.
The Times story quotes a South Korean government official as saying that the attack in his country was launched by about 18,000 zombie computers in South Korea infected by a well-know DDoS hacker program, while an unnamed US government official was quoted in the Washington Post this morning as saying,
"It certainly seems to be a well-organized attack. ... There are a lot of computers involved. What we don't know is who is orchestrating it."
I think it is unlikely that the US and South Korea, who are close allies, were randomly selected.