North Korea has successfully produced a nuclear warhead small enough to fit onto a ballistic missile, according to a report by the Washington Post Tuesday.

The report cited a confidential assessment by US intelligence officials the Defense Intelligence Agency.

“The IC [intelligence community] assesses North Korea has produced nuclear weapons for ballistic missile delivery, to include delivery by ICBM-class missiles,” the Washington Post reported the assessment as saying.

The US believes that North Korea currently possesses approximately 60 nuclear weapons. However, the size of the warheads meant that they could not be fitted onto missiles capable of the threatening the US.

The assessment on North Korea's latest breakthrough puts the US within range of a North Korean nuclear strike if the rogue regime places a nuclear warhead on an Intercontinental Ballistic Missile (ICBM).

Last month, a top US general stated that North Korea "clearly" had the capability to strike parts of the US with an ICBM. The rogue nation has repeatedly test-fired ballistic missiles recently.