The United States' Vice Chief of Naval Operations Admiral Robert Burke says North Korean submarine-launched ballistic missiles(SLBM) must not be underestimated, saying such weapons could pose a direct threat to the U.S. mainland. 

Radio Free Asia said Monday that Burke made the assessment when he spoke at the annual Military Reporters and Editors conference at Navy League headquarters in Arlington, Virginia last Friday.  

Burke stressed the need to keep a close eye on the North’s SLBM development capacity, stressing it could be a "game changer." 

He was quick to add, however, that it’s not certain whether an SLBM the North tested early this month was actually fired from a submarine.  

On October third, North Korean state media said the Academy of Defense Science succeeded in test-firing a "new-type SLBM Pukguksong-3" in waters just off the country's east coast the previous day.