The FBI has found breaches in Illinois and Arizona voter registration databases and is urging states to increase computer security ahead of the November presidential election.
On Monday, Matt Roberts, spokesman for Arizona Secretary of State Michele Reagan, described the threat as “credible” and significant, “an eight on a scale of one to 10,” .
Officials and cyber security experts say recent breaches at the Democratic National Committee and elsewhere in the Democratic Party were likely carried out by people within the Russian government.
Kremlin officials have denied allegations of Moscow's involvement.