I believe my websites are under a new kind of invalid traffic attack that generates invalid clicks on Adsense. There has been some news report on this recently:
Our websites are based in south america, and all of a sudden last week we started receiving high traffic with over 90% bounce rate and ridiculous CTRs on Adsense for United States. US is not a targeted audience at all.
I wonder if there is any way we can intensify bot filtering specifically for US IPs?
What would you guys do in my position?
I would not suggest filtering IP from USA coz most of the IP for google/adsense visits from US. They wont be able to read the content on your site. + Most other third party ad checker like moatads or grapeshot wont be able to access your site and it will definitely decrease your revenue.