U.S. Defense Secretary James Mattis says that the U.S. takes the threat of North Korea's ballistic missiles "very seriously." 

Speaking at a press conference in Alaska en route to Asia on Tuesday, Mattis said that North Korea's ability to launch intercontinental ballistic missiles still exists today, so clearly the U.S. takes that very seriously.

The defense chief added that hopes are riding with diplomats and expected to see progress in the days and weeks ahead.

When asked if he was confident in the U.S. missile defense system, Mattis said that he's absolutely confident the system will work. 

Mattis arrived in Beijing Tuesday. ​He is due to arrive in Seoul on Thursday for talks with South Korean Defense Minister Song Young-moo. 

[Photo : YONHAP News]