The Democratic People's Republic of Korea (DPRK) has reportedly conducted an unsuccessful test firing of a ballistic missile from a Sinpo-class submarine off the country’s eastern coast on Saturday.

The test launch comes a day after the US and South Korea joined forces to deploy the Terminal High-Altitude Area Defense (THAAD) system to counter North Korean missiles. North Korea has also threatened a ‘physical response’ to the THAAD deployment in South Korea.

Media reports cited a statement from South Korea's Joint Chiefs of Staff and the US Strategic Command that said ‘the missile was successfully launched but failed in its early flight stage’.

"Our commitment to the defence of our allies in the face of these threats remains ironclad."

Reuters reported a statement from US Strategic Command that confirmed a KN-11 submarine-launched ballistic missile was tracked over the Sea of Japan "where initial indications are it fell".

US State Department Bureau of East Asian and Pacific Affairs spokeswoman Gabrielle Price was quoted by CNN as saying: "We strongly condemn North Korea's missile test in violation of UN Security Council Resolutions, which explicitly prohibit North Korea's use of ballistic missile technology.

"These actions, and North Korea's continued pursuit of ballistic missile and nuclear weapons capabilities, pose a significant threat to the United States, our allies, and to the stability of the greater Asia-Pacific," she said.

"Our commitment to the defence of our allies in the face of these threats remains ironclad."

In March this year, the UN Security Council imposed new sanctions on North Korea following its nuclear tests and rocket launch.

Last week, the US decided to blacklist North Korean leader, Kim Jong-un, and ten other officials for human rights abuses.