The IRS has been doing this for years to US citizens living overseas. If you have 10k or mote in an account, you have to file a FBAR form every year. Failure to do so could result in a 10K fine and 3 years in jail. You have to file a form for each account. One year I had a little over 10K in an account. I transferred this money to different banks 3 times in one year. Thus 3 forms. They came back to me claiming I had 30K in accounts and comparing it to the previous year where I only had one account, they claimed I made an extra 20K that wasn't reported on my income tax form. Took me 6 months to straighten it out with these idiots.
And the penalty for failure to report the foreign accounts is 50% of the highest balance in the account during the year.
In your case it would be $10,000 x 50% x 3 accounts or $15,000 per year. They usually hit multiple years.
Thus it is easy to accidently create a liability far greater than the account balance and they end up seizing your other US bank accounts to pay the penalty.