Some overall details;
A book series I listened to as audiobooks in 2019-2022. They were newish books so published in the range 2010-2022. It had somewhere around 3 - 4 books. There was never a large scale invasion, unless some new books came out. Very technical and focused on the normal world trying to prove, find, and kill / capture these 5-7(?) aliens.
These aliens had incredibly advanced technology, and I believe all or most of them were heavily genetically modified AND cyborgs as well. They were outfitted and sent by a far away planet to destabilize Earth by any means possible, this was actually a planet and not a galactic federation or anything like that.
The series has subsequent phases of trying to prove these aliens exist, trying to convince increasingly senior people (i.e. secretary of state, CIA head) to believe this threat, how to deal with the incoming enemy fleet, and tracking down these infiltrators.
As the series goes on, it becomes increasingly obvious that;
A. There is an alien threat killing important people and destabilizing regions.
B. Earth is not responding fast enough to the threat.
The general gist is that the infiltrators are on an honor-suicide mission, and as long as the humans don't fully turn their attention to the incoming threat, the incoming fleet will be successful.
Some of the technology / story notes:
- Genetically modified to be an unassuming human from whatever continent they were to attack (one was Indian, one was Chinese, etc.)
- "Sub-space tweeters"(?) Morse code like communicators that were the only way to talk FTL, I think using quantum entanglement. I think they has pocket versions that relayed to hidden satellites, that then used a more powerful version to send to fleet.
- Panel / pixel based armour that acted as very effective, multi-wavelength (i.e. infrared) camouflage, this was separated from their genetic modifications and more of a war tool.
- I'm pretty confident there were 6-7 factions of aliens relating to continents on the other planet, I remember that 1 was specifically a rich nomadic seafaring race and the others were resource and war hungry (this is important for spoilers).
Spoiler-ish details: Don't read below if you find that interesting and don't know the book name
- Pretty far into the series, you find out that the nomadic race actually sent a double agent AND tipped off the original characters to the threat. They didn't agree with stealing an entire planet and had some bad blood about the other factions doing the exact same thing to them (minus the interstellar travel).
- The final alien was caught only after it detonated a nuke in either Texas or Florida.
- I don't remember exactly what they did, but the killed almost all the fleet in an asteroid or missile strike that was made possible with technical information given by nomadic faction; as well as an inside strike and suicide attack by this same faction against the attack fleet. They never made it Earth, or more accurately they didn't survive (Newton's 3rd...).
I feel like this is a pretty good synopsis, and if you don't know the book - I'm sorry for ruining portions of it. It's a fantastic book / series.