Leader Kim Jong Un supervised the test of the missile, called "Pulhwasal-3-31," which is identical to the strategic cruise missiles that the North said last week were under development.
State news agency KCNA and official Rodong Sinmun newspaper said the missiles flew above the sea off the country's east coast for 7,421 seconds and 7,445 seconds and hit an unspecified island target, indicating the flight time exceeded two hours.
Leader Kim called the test a success, KCNA said, "which is of strategic significance in carrying out the plan...for modernizing the army which aims at building a powerful naval force."
Last week, the North said it had tested a new strategic cruise missile, indicating it was designed to carry a nuclear warhead, but at the time did not mention it was being developed for submarine launch.