North Korea has enough material to produce about 45 nuclear weapons, but North Korea has no way of reaching the mainland US yet, said American scientist Dr. Siegfried Hecker.

Hecker, who formerly ran a weapons laboratory at Los Alamos in the United States, believes North Korea's nuclear missiles could reach South Korea and most of Japan, Express reported.

The scientist believes that more tests are required for some missiles to prove their usefulness from a military point of view.

According to Hecker, US President Donald Trump missed the opportunity to suspend North Korea's nuclear program in 2019.