The government has lifted the nation's cyber crisis alert level by one notch as of 6 p.m. Thursday.

The Ministry of Science, ICT and Future Planning said the move is to prepare against possible North Korean cyber attacks during South Korea-U.S. joint military exercises. The ministry added it's also trying to protect against an increase in hacking attempts on South Korean agencies and organizations.

The ministry said the government has taken swift response measures against increasing cyber attacks in the form of the so-called DDoS(distributed denial of service) attacks or Web site defacement.

It said state agencies are also strengthening preemptive measures including surveillance of key infrastructure and monitoring of corporate Web sites.

The alert is now a level three of the five-tier system, with level one being the highest warning.