North Korea may not yet have mastered the re-entry technology necessary to deliver a payload aboard an intercontinental missile (ICBM), South Korea’s defense chief said on Monday.

“It’s too early to see [Friday’s launch] as a test of re-entry technology,” South Korean Minister of National Defense Song Yong-moo told lawmakers during an emergency meeting of the National Assembly’s National Defense Committee.

Re-entry technology, which allows a missile warhead to survive the heat and pressure sustained when reentering the Earth’s atmosphere, is a key technological threshold required in order to field a reliable ICBM force.

Monday’s emergency meeting of the National Defense