A researcher at the U.S.-based Heritage Foundation says Washington should consider South Korea's request to extend its own permissible limits on missile development in order to counter the increasing threat of North Korean ballistic missiles.

Senior researcher for Northeast Asia, Bruce Klingner, on Friday proposed that Washington jointly enhance missile defense capabilities with Seoul, noting that the North recently established an independent military division responsible for controlling its intermediate-range ballistic missiles.

Under an agreement with the U.S., South Korea cannot possess missiles with ranges exceeding 300 kilometers.

Klingner says that the moves should be considered as diplomatic efforts to constrain North Korea's advancing missile and nuclear weapons capabilities have failed.