The U.S. Department of Homeland Security (DHS) on Friday notified the chief election officer or secretaries of state in 21 states that hackers targeted their states' election systems before last year's U.S. presidential election.
The notification came roughly a full year after ABC News reported that "more than 20" states' had been targeted.
"Hackers working on behalf of the Russian government are suspected in the onslaught against more than 20 state election systems, according to sources with knowledge of the matter," ABC News reported in September last year.
The states targeted are Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, Florida, Illinois, Iowa, Maryland, Minnesota, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Texas, Virginia, Washington and Wisconsin, according to Fox News.
"It is completely unacceptable that it has taken DHS over a year to inform our office of Russian scanning of our systems, despite our repeated requests for information," California Secretary of State Alex Padilla said Friday in a statement.
"The practice of withholding critical information from elections officials is a detriment to the security of our elections and our democracy," Padilla said.
Some of the election officials who were informed by DHS said Friday the hacking attempts could be linked to Russia, for example, targeted by "Russian cyber actors."
Alaska Elections Division Director Josie Bahnke said computers in Russia were scanning election systems looking for vulnerabilities.
Federal officials said that in most of the 21 states, the targeting was preparatory activity such as scanning computer systems, according to local media reports.
"Scanning is an unauthorized attempt to identify weaknesses in a computer or network -- akin to a burglar looking for unlocked doors in a house," said Padilla.
In most cases, states said they were told the systems were not breached. Illinois reported that hackers had succeeded in breaching its voter systems.
"There are constant attempts by bad actors to hack our systems," Iowa Secretary of State Paul Pate, a Republican, said in a statement. "But we continue to deflect those attempts."
In a letter sent to Admiral Michael S. Rogers of the National Security Agency (NSA) earlier this year in June, Padilla said he had expressed serious concern about NSA's failure to provide timely and critical information to America's elections officials.
"We shouldn't have to learn about potential threats from leaked NSA documents or media reports. It is the intelligence community's responsibility to inform elections officials of any potential threats to our elections. They failed in this responsibility," said Padilla.
Earlier this year, a leaked NSA report outlined a Russian effort to hack into devices made by a Florida-based voting software company, according to the Los Angeles Times.
DHS testified earlier this year before the U.S. Senate Intelligence Committee that "the owners of the systems within those 21 states have been notified," said Padilla, who thought "this was simply not true and DHS acknowledged they failed to contact us and 'two or three' other states."
U.S. President Donald Trump, a Republican who defeated Democrat Hillary Clinton in the presidential election, has called the Russia story a hoax.