The four-minute video, titled A Short, Three-Day War, begins with images of a massive artillery and rocket barrage, followed by a large-scale land and air assault with North Korean troops streaming over the border solar executive gifts and premium.
A male narrator describes how "crack stormtroops will occupy Seoul and other cities and take 150,000 US citizens as hostages".
The video was posted on the North's official website on Friday.
It comes at a time of escalating tensions on the Korean peninsula, with multiple threats from North Korea of an armed response to South Korea-US military drills and to UN sanctions imposed after its nuclear test last month KD furniture.
On Thursday, the North Korean military threatened strikes on US military bases in Japan and Guam.
The narrator describes different stages of the invasion, including the destruction of forces under the US Pacific Command with "powerful weapons of mass destruction".
The video shows paratroopers jumping from the sky superimposed over an aerial shot of the South Korean capital, white wine with North Korean military helicopters hovering overhead.
On the third day of the proposed invasion, the narrator says Seoul and other cities will be in a state of total chaos, with no food or water supplies, and no communications network.
At this point the Korean People's Army would step in to "stabilise" the situation.
According to official immigration figures, South Korea has an American population of more than 130,000 civilians and 28,000 troops.