North Korea may conduct another missile test within days, after more than two months of silence, a new report has claimed.

The US now has evidence that Japanese reports of an impending test are true, a US government source told Reuters. Japan recently detected suspicious radio signals coming from North Korea, and a source told the Japan Times that the country "might launch a missile within the next few days".

South Korea's Yonhap news agency also made similar claims, citing South Korean government sources.

Other US officials, however, noted that North Korea is known to falsely signal such tests, in order to disguise their true plans. The signals detected by Japan are also not unusual, and may be related to North Korean military training.

North Korea last fired a ballistic missile over Japan in September. They tested missiles at a rate of two to three a month over the summer, but paused after the 15 September launch.

Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Show all 6 1 /6 Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Photos released by North Korea show Kim Jong-un talking to subordinates next to a device thought to be the new thermonuclear weapon. There is no way of independently verifying the pictures STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korea claims it has successfully tested an advanced hydrogen bomb which could be loaded onto an intercontinental ballistic missile AFP/Getty Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A diagram on the wall behind Mr Kim shows a bomb mounted inside a cone STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korean leader Kim Jong-Un (C) attending a photo session with participants of the fourth conference of active secretaries of primary organisations of the youth league of the Korean People's Army (KPA) in Pyongyang STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters

The US recently returned North Korea to its list of state sponsors of terror – a position it had not occupied since 2008. The decision imposed new, more stringent sanctions on the country.

Pyongyang called the decision a "serious provocation," and said the country “must continue to keep the treasured nuclear sword in our hands more tightly" in a statement to its state-run news agency.

While North Korea has not conducted a missile test in months, it has been regularly testing engines and fuels, South Korean Unification Minister Cho Myoung-gyon told reporters on Tuesday. South Korea is still trying to determine whether these actions are related to missile or nuclear tests.

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Mr Cho also warned that the North could become fully nuclear capable within the next year.

“North Korea has been developing its nuclear weapons at a faster-than-expected pace," he said. "We cannot rule out the possibility that North Korea could announce its completion of a clear force within one year."

A series of troubling news reports sprang from the country this year, as experts warned that North Korea was rapidly developing its nuclear weapons programme.

In August, the Washington Post reported that North Korea had produced a nuclear warhead capable of fitting into one of its missiles. The chairman of the US Joint Chiefs of Staff, Marine Corps General Joseph Dunford, warned in September that these missiles will be capable of reaching the US in a "very short time".