Operation Impending Doom II is the Irkens' second attempt to take over the universe due to Zim botching the first attempt and killing all of the former Invaders. Of course, because of this Zim was sent far away to Earth by Tallest Red and Tallest Purple, ensuring he wouldn't ruin things the second time around.
So far, however, Zim has still managed to make things more difficult for the Armada, most notably by commandeering the Massive in "Backseat Drivers from Beyond the Stars," and leaving Mars to fly wildly through space and destroy many Irken vessels in "Battle of the Planets".
Despite this, plans for Irken galactic conquest seem to be going pretty smoothly, with two planets confirmed as conquered, and three others likely to be conquered (as suggested in "Planet Jackers"). Additionally, at least eleven other worlds may have been conquered offscreen, as "Backseat Drivers from Beyond the Stars" implied that all members of the Resisty come from planets that have been conquered by the Irkens.
Had the series not been cancelled, there would have been an untitled season two finale in which Operation Impending Doom II was put on temporary hold due to Invader Tenn being captured on Meekrob (thanks to the insane SIR units sent to her in "Megadoomer" by a rebellious slave). All the other Invaders, excluding Zim (though Skoodge fields Zim the information on Tenn's capture), would have been ordered to attempt a rescue by the Almighty Tallest. It can be assumed that afterwards, the Invaders would have gone back to their assigned planets to continue the operation, or the operation would have been permanently called off after Zim discovers the beauty in life on a certain planet.
In Issue 43, Planet Plim is conquered by the Irkens after Dib inadvertently exposes its location to them when he takes down the anti-technology cloaking field around the planet in an attempt to free the natives from being stuck on the planet. This makes it the only planet conquered during Impending Doom II not specifically targeted for it (as the Irkens had been searching for it in vain for centuries beforehand), and the only planet conquered not as the result of an Invader's actions (though Dib, who was wearing an Irken costume at the time in order to beat the more popular Zim in winning over the Plim, is mistaken for an Invader and given credit for the conquest).
During the events of Invader Zim: Enter the Florpus, it was revealed that due to the Tallest' laziness, all the planets marked for conquest are in a straight line (and any planet not marked that gets in their path is destroyed). As a result of their refusal to change course, the status of Operation Impeding Doom II is currently unknown after the Tallest, as well as the rest of the Irken Armada, were sucked into a Florpus Hole, trapping them (or equally likely killing them, as suggested by Jhonen Vasquez), leaving the Irken Empire leaderless.
|Invader||Mission Planet||Mission Status|
|Flobee||Rock Planet||Presumably complete|
|Skutch||Striped Planet||Presumably complete|
|Slacks||Boodie Nen||Still in operation|
|Stink||Spotted Planet||Presumably complete|
|Zim||Earth||Failing; in exile|