North Korea is a "powerful nuclear weapons state ready to detonate self-reliant A-bomb and H-bomb to reliably defend its sovereignty," the official KCNA news agency quoted Kim as saying on Thursday.
Kim made the remarks during a visit to the Phyongchon Revolutionary Site in the capital, Pyongyang. The military site is historic as it is home to the country’s first arms firm built in 1945.
"We can further build up our country into a powerful one no enemy dare to provoke," the North’s leader said.
Pyongyang has so far tested three atomic devices that relied on nuclear fission. A hydrogen bomb makes a more powerful explosion as it uses fusion in a chain reaction. North Korea's nuclear tests in 2006 and 2009 were with plutonium devices. Its third test in 2013 was believed to have used uranium.