Pyongyang, North Korea - North Korea's test of a solid-fuel intercontinental ballistic missile (ICBM) should serve as a warning to the US and its allies, ruler Kim Jong Un said, according to state-run media on Tuesday.

The launch of the Hwasong-18 on Monday sent a "clear signal to the hostile forces," said Kim, who oversaw the launch of the missile with a range that allows it in theory to hit anywhere in the United States.

Depending on their design, the missiles can be equipped with a nuclear warhead. On Monday, the missile flew some 620 miles from a steep launch angle before falling into the sea.

"The successful drill is a practical demonstration of the actual condition and reliability of the formidable striking capabilities and absolute nuclear war deterrent possessed by the armed forces," Kim said, according to the Korean Central News Agency (KCNA).

The missile shows "what option the DPRK would take when Washington makes a wrong decision against it," he said, using the acronym of the Democratic People's Republic of Korea.

The Hwasong-18 was first tested in April.

The US, South Korea, and Japan condemned Monday's test as a provocation and a clear violation of UN Security Council resolutions that prohibit North Korean nuclear and missile activities.

The regime has tested missiles several times this year. North Korea often says the launches are a response to joint military exercises by the US and South Korea.

Seoul announced on Tuesday that a system to detect and assess North Korea's missile launches in real-time had been put into operation.

It allows South Korea, Japan, and the US to quickly share data. The three allies announced back in August they were taking the step as a way of boosting defense cooperation.