A feasibility study on adopting a land-based Aegis missile defense system to deal with North Korea's missiles will be expedited, government sources said.

The idea to add the Aegis Ashore system to the nation's multi-tiered ballistic missile defenses is aimed at dealing with what Tokyo calls the "new level of threat" posed by North Korea's weapons programs. Deployment could take place several years from now, the sources said Friday.

The government has also considered adopting the state-of-the-art Terminal High Altitude Area Defense missile shield system but decided to focus on Aegis Ashore, which is less expensive and has a broader defense range.