The Federal Bureau of Investigation warned Monday that at least two state government election board websites were hacked by foreign attackers.

State board websites in Arizona and Illinois are believed to be the websites that were breached, according to Yahoo. The hacks are suspected to be of either Russian or Turkish actors.

Wired reports that hackers could “destabilize American politics.”

“Someone is trying to hack these databases, and they succeeded in exfiltrating data, which is significant in itself,” says Thomas Rid, a cybersecurity-focused professor in the War Studies department at King’s College of London and author of Rise of the Machines. “In the context of all the other attempts to interfere with this election, it’s a big deal.” In its warning sent to state-level election boards, the FBI described an attack on at least one of those two election websites as using a technique called SQL injection. It’s a common trick, which works by entering code into an entry field on a website that’s only meant to receive data inputs, triggering commands on the site’s backend and sometimes giving the attacker unintended access to the site’s server. In this case, it seems to have allowed the hackers to steal 200,000 voter records from the Illinois board of elections, and to cause the Illinois board to close registration for ten days.

In an op-ed published at Breitbart earlier last week, George Washing University Public Interest Law Professor John Banzhaf warned about the vulnerability of our voting system to hackers — including those who could be in the pay of a foreign government.