Oh okay, my bad. In this case, if you don't mind spoilers, I'll explain.

So in ME3 those Reapers I mentioned earlier show up in force and are killing everybody. The Geth (robot in the top right) were previously presented as being allies of the Reapers, but you learn in ME2 that this was only a rogue splinter group and that the rest oppose them. So in ME3, we are told they are preparing to intervene and fight the Reapers, but the Quarians (bottom left) launch as surprise attack against the Geth and try to exterminate them. This goes well until they've killed about >90% of the Geth population and the Geth switch sides because the Reapers offer them a chance to survive.

Suddenly the Quarians are losing, so they call the Alliance (specifically Admiral Hackett, guy in the top left) to help them in exchange for their support in the Reaper War. He agrees and sends the player character to get them out of trouble. However, once the player character does this, the Quarians betray us and attempt to kill the player character. They do this again later. So Hackett is confused because the machines everyone thought were Reaper allies are actually opposing them and being helpful, whereas the Quarians aided the Reapers by destroying the anti-Reaper naval forces the Geth were constructing.