Russian government hackers attempted to hack the election systems of 21 states, including California, Florida, Ohio and Wisconsin, during the 2016 election, the US Department of Homeland Security (DHS) notified on Friday (22 September). The DHS confirmed that it had notified the states but has not identified them publicly. The announcement comes nearly 10 months after Election Day.

"As part of our ongoing information sharing efforts, today DHS notified the Secretary of State or other chief election officer in each state of any potential targeting we were aware of in their state leading up to the 2016 election," DHS spokesman Scott McConnell said in statement. "We will continue to keep this information confidential and defer to each state whether it wishes to make it public or not."

However, several states including Alabama, Alaska, Colorado, Connecticut, Florida, Minnesota, Texas and Washington state confirmed to Reuters that they were targeted by hackers but weren't successful. The Associated Press confirmed that Illinois, Iowa, Maryland, North Dakota, Pennsylvania, Delaware, Oregon, Oklahoma, and Virginia were also targeted.

Many said they were not aware until they were notified by the DHS. Last year, Arizona and Illinois confirmed that they were targeted as well.

The DHS said only preliminary activity by hackers, such as scanning computers, was observed in most of the 21 states with a small number of networks compromised. Judd Choate, president of the US National Association of State Election Directors, said there is currently no evidence that Russia "altered one vote or changed one registration", Reuters reports.

In January, US intelligence agencies concluded that Russian President Vladimir Putin ordered a complex "influence campaign" that included cyberattacks, disinformation campaigns and leaks to undermine American democracy, denigrate Hillary Clinton and help sway the vote in Donald Trump's favour.

The Kremlin has dismissed the allegations and denied any involvement in the DNC hack. Several congressional committees are currently investigating the alleged Russian meddling and whether the Trump campaign colluded with Moscow. President Trump has continued to describe the ongoing Russia probe as a "witch-hunt" and a "hoax".

Many lawmakers slammed the DHS for taking so long to notify states that their election systems were targeted.

"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," Democratic California Secretary of State Alex Padilla said in a statement. "The practice of withholding critical information from elections officials is a detriment to the security of our elections and our democracy."

Senator Mark Warner, the top Democrat on a committee currently investigating Russian meddling in the election said it is "unacceptable that it took almost a year after the election to notify states that their elections systems were targeted".