The commander of the U.S. Indo-Pacific Command said Tuesday that North Korea has yet to demonstrate atmospheric reentry technology for its intercontinental ballistic missiles(ICBM).

Adm. Samuel Paparo made the remarks during a forum at the Brookings Institution in Washington when asked if North Korea had reentry capabilities. 

Paparo said the U.S. has not yet seen any such capabilities, but it is seeing continued testing toward that goal. 

Atmospheric reentry technology is necessary for a missile’s warhead to withstand extremely high temperatures during reentry to Earth’s atmosphere.

The commander said the ICBM that North Korea test-fired reached an altitude higher than seven thousand kilometers, hinting that the North might have the ability to put the entire U.S. mainland in its target range.

Paparo also said that North Korea could get submarine and propulsion technologies in return for supplying weapons and dispatching troops to Russia.