North Korea claims more progress in missile development

North Korea fired five short-range projectiles off its east coast on Monday, three days after it launched its first medium-range ballistic missile into the sea since early 2014, according to Seoul officials.

In an apparent effort to prove its claims of boosted nuclear capability, North Korea has also disclosed purported mock-up of a nuclear warhead and claimed to have developed a re-entry vehicle for a missile that is needed to return warhead to the atmosphere from space so it could hit its intended target.

The re-entry vehicle is considered one of the last major technologies North Korea must master to develop long-range missiles equipped with nuclear weapons capable of reaching the U.S. mainland.