SEOUL (REUTERS/AFP) - ​North Korean leader Kim Jong Un says the launch of its Hwasong-12 intermediate-range ballistic missile on Tuesday (Aug 29) was like a "real war" and a "meaningful prelude to containing Guam".

"The current ballistic rocket launching drill like a real war is the first step of the military operation of the KPA in the Pacific and a meaningful prelude to containing Guam," the North's official KCNA news agency quoted Kim as saying on Wednesday.

KPA stands for the Korean People's Army, the North's military.

Kim guided the launch in a drill to counter the joint military exercises by South Korean and US militaries, KCNA said.

North Korea hinted at another reason Japan was in its sights: history.

The missile, it said Wednesday, was timed to mark the 107th anniversary of the "disgraceful" Japan-Korea treaty of 1910, under which Tokyo colonised the Korean peninsula.

The North's official KCNA news service said leader Kim Jong Un "gave vent to the long-pent grudge of the Korean people" with "a bold plan to make the cruel Japanese islanders insensible on bloody Aug 29".

Japan's colonisation of a then-unified Korea ushered in a period of oppressive rule that only ended with Tokyo's defeat in WWII.

The Imperial army forced thousands of Korean women to work as sex slaves in military brothels during the war, a practice that weighs heavily on ties with both Koreas today.

North Korea threatened to fire four Hwasong-12 missiles into the sea near the US Pacific territory of Guam earlier this month after US President Donald Trump said the North would face "fire and fury" if it threatened the United States.

Shortly before the North Korean statement, Trump said that "all options" were on the table, reviving his implied threat of pre-emptive US military action just days after congratulating himself that North Korea's Kim appeared to be "starting to respect" him by holding off on missile firings.

South Korea's military said on Tuesday that the missile had travelled around 2,700 kilometres (1,700 miles) and reached a maximum altitude of 550 kilometres.

North Korea has twice previously sent rockets over the main islands of Japan, in 1998 and 2009, but on both occasions claimed they were space launch vehicles.

"The drill had no impact on the security of the neighbouring countries," KCNA insisted, adding that Kim expressed "great satisfaction" over the launch. There would be "more ballistic rocket launching drills with the Pacific as a target in the future", it cited him as saying.