North Korea says it carried out a 'super-large' rocket launcher test on Tuesday (September 10).
State TV showed photos of Kim Jong Un himself overseeing the launch.
The timing would mean Pyongyang tested the weapon the same day as a testfire of twin short-range projectiles, hours after Pyongyang signalled was open to resuming talks with Washington.
Kim has guided testing of the same multiple rocket launcher before.
The North had held back on weapons tests for over a year, but its now had at least eight launches since Kim met President Donald Trump in June.
Analysts tell Reuters that North Korea carries out weapons tests for many reasons, including reassurance for its own defense establishment.
However, they say Tuesday's launches appeared timed to send a message to Washington, potentially to demonstrate what may happen if the U.S. doesn't come to the table with proposals the North sees as realistic.
President Donald Trump has played down this year's tests.
He says he doesn't believe short-range missiles violate any agreements.
However, John Bolton, the Trump national security advisor who was ousted on Tuesday, has said those short-range launches are banned under UN resolutions.