North Korea has been conducting a series of missile tests, the first on July 4 and again on July 28.
There has been speculation as to whether the rogue state had developed the capability of a re-entry vehicle for the nuclear warhead that can withstand the temperatures of Earth’s atmosphere as it re-enters the planet.
According to senior intelligence analyst for ballistic missiles at the Air and Space Intelligence Centre, Tom Boyd, North Korea is on the cusp of developing the technology.
When asked how long it will take for North Korea to really threaten the US homeland he said: “Probably several more flight tests, but ultimately if they want to have confidence that the system works as intended they have to flight test it and prove that reentry vehicle can survive realistic reentry conditions.”
US intelligence also estimates that could happen as early as next year due to the rate of the nuclear tests.
The rogue state cannot attack the US with a nuclear weapon until it develops the re-entry vehicle.
But, Mr Boyd said it is “inevitable” that the hermit kingdom will develop the technology.
He said: “If you are not willing to fail in the ballistic missile or space launch vehicle missiles business, you’re in the wrong business… It’s almost inevitable, these are highly complex systems, and failures are pretty much inevitable.”
The North Korea’s ICBM is called the “Hwasong”, which translates as Mars, the Roman God of War.
Mr Boyd has described them as a “challenging target”.
He added: “They’ve been referred to as the ultimate weapon. They get to the target very quickly. An ICBM has a reentry velocity on the order of four to five miles per second, so there’s very little time to react.”
It comes as US Defence chief Jim Mattis admitted the threat of a North Korean nuclear missile attack is accelerating every day.
During a tour of Asia, the US general said the threat of nuclear missile attack by North Korea increasingly likely.
With South Korean Defence Minister Song Young-moo at his side, Mr Mattis accused North Korea of acting like “outlaws”.
Mr Mattis said: “North Korea has accelerated the threat that it poses to its neighbours and the world through its illegal and unnecessary missile and nuclear weapons programs.”