I think the 38% number is definitely wrong, maybe even wrong by one order of magnitude.
I tried fact-checking and came up with this:
https://providencemag.com/2018/04/what-a-country-immigrants-serve-us-military-well
Few Americans realize that 65,000 immigrants serve in the US military today. That number includes some 18,700 troops who hold green cards (in other words, legal permanent residents who are not yet naturalized citizens). According to the Pentagon, about 5,000 such residents enlist each year.
Since the total number of the US armed forces is around 1.3 million, it follows that 38% is definitely wrong and the correct number of immigrants is likely around 5%.
I think the 38% number originates from service member naturalization stats or service member family stats and has been mis-interpreted. Can’t tell for sure, didn’t hire a spy to find out. :)
P.S. Edit: found a secondary source with similar data:
https://www.usafis.org/can-i-join-the-us-military-as-a-green-card-holder/
Approximately 8,000 Green Card holders join the US military each year and around 35,000 are currently serving on active duty.
Since green card holders aren’t the only variety of immigrant, the number 65 000 seems plausible.
What I notice in the comments of the county officials: some of them claimed “it could not have been prevented, even with radar”.
Here in Eastern Europe, a weather radar makes a full turn in 5 minutes and I think that faster ones exist in fancier places. An SMS takes at most 15 minutes to deliver, with some arriving in seconds and some trailing behind if the network is under load.
Also, I’m sure some US states get even tornados, and are damn quick at sending out alerts about those things… so the diagnosis is “as usual, people ignored a considerable risk”. They had not set up automation. People could have been alerted, tech for that exists already for a decade or more.