Traced to PLO?

Yeah right. As the article states, it isn't in the interest of the PLO to show their hand. If a system was taken off line, it was either that Chinese MilHats made a mistake (port scanner set too aggresively and causing DOS, buffer overflow exploit against wrong version exe crashing machine, etc), or (more likely) that some kid happened to zombie a machine in an unclassified .mil.ca network and used that as a proxy to do some playing around in the Pentagon.

War Games 2? :-)