North Korea released a new propaganda video Saturday showing a nuclear strike on Washington and then threatened South Korea with a “merciless military strike” for slandering leader Kim Jong-Un. Menacingly titled “Last Chance,” the video released on Saturday shows a submarine-launched nuclear missile laying waste to Washington and concludes with the US flag in flames.

The four-minute video romps through the history of US-Korean relations and ends with a digitally manipulated sequence showing a missile surging through clouds, swerving back to Earth and slamming down in front of Washington’s Lincoln Memorial. The US Capitol building explodes in the impact and a message flashes up on the screen in Korean: “If US imperialists budge an inch toward us, we will immediately hit them with nuclear (weapons).”

North Korea has been pushing to acquire a submarine-launched ballistic missile (SLBM) capability which would take its nuclear strike threat to a new level, allowing deployment far beyond the Korean peninsula and the potential to retaliate in the event of a nuclear attack.

On Thursday, Kim presided over a huge, long-range artillery drill simulating a strike on Park’s office and official residence in Seoul. And on Saturday, the artillery section of the Korean People’s Army (KPA) issued an “ultimatum” demanding Park apologise and punish those who formulated the decapitation strategy.

“If matchless traitor Park Geun-Hye and her group do not respond … the long-range artillery force of the KPA large combined unit on the front will move over to merciless military action,” it said in a statement carried by the North’s official KCNA news agency.