A U.S. weekly devoted to military news says Washington has successfully developed a new missile warhead that is capable of penetrating deeper underground than existing bunker buster bombs.

The Defense News said the new missile warhead is apparently aimed at secret underground nuclear facilities of North Korea.

The reports added once the development project is completed after one year, the U.S. military will deploy six such missiles to the U.S. forces stationed in South Korea.

The magazine said that the successful development of the underground-penetrating missile would give the U.S. a strategic leverage toward the North's nuclear facilities allegedly hidden deep underground.