North Korean leader Kim Jong Un oversaw the test of a "super-large multiple rocket launcher" on Saturday, state news agency KCNA reported on Sunday.
North Korea fired what appeared to be two short-range ballistic missiles into the sea off its east coast, the South Korean military said, the latest in a series of launches in recent weeks amid stalled denuclearisation talks.
Photos released by North Korean state media showed rockets launching from large tubes mounted on the back of an eight-wheel vehicle.
Analysts said it appeared to be at least the fourth new missile system unveiled by North Korea since denuclearisation talks stalled at a February summit between Mr Kim and US President Donald Trump.
North Korea must step up development of new strategic and tactical weapons to counter "ever-mounting military threats and pressure offensive of the hostile forces," Mr Kim said on Saturday, according to KCNA.
North Korea's young defence scientists who developed the missiles are a "precious treasure and wealth of the country which cannot be bartered for anything," Mr Kim said.
On Saturday, a KCNA commentary said North Korea "will never barter the strategic security of the country for the sanctions relief."
American officials have been trying to restart the stalled talks with North Korea over its nuclear weapons and ballistic missile programmes, which are heavily sanctioned.
After the latest tests, Trump again touted his good relationship with Kim and said the North Korean leader had been "pretty straight with me."
On Saturday, the country launched another series of missiles, the latest in the most prolific series of tests since President Trump took office.
South Korea’s defence ministry said two missiles were launched from south Hamkyong. They landed outside Japan’s exclusive economic zone, Japan’s Coast Guard said in a statement. The US assessed that two short-range missiles were fired in the direction of the Sea of Japan, about 15 minutes apart, officials told CNN.
Mr Kim’s regime has conducted a series of short-range ballistic missile tests in recent weeks as he seeks a more favourable negotiating framework in nuclear talks with Mr Trump. The US leader has said the tests shouldn’t disrupt talks, so long as Mr Kim doesn’t launch longer-range missiles that could strike the US
