Wisconsin, Ohio, California and 10 other states said on Friday they were among 21 states that Russian government hackers targeted in an effort to sway the 2016 presidential election in favor of Donald Trump though no votes were changed.

The Department of Homeland Security confirmed it had notified the states of the activity but declined to identify them. Russia has denied election meddling, and President Trump has denied any collusion with Russia.

Alabama, Alaska, Colorado, Connecticut, Florida, Minnesota, Texas and Washington state also confirmed they were targeted by Russian hackers but said they were not successful. Arizona and Illinois confirmed last year that they were targets.

The Associated Press confirmed Iowa, Maryland, North Dakota, Pennsylvania, Delaware, Oregon, Oklahoma and Virginia were also targets, bringing the total states identified to 21. Those states did not immediately return messages seeking comment late Friday.

“There remains no evidence that the Russians altered one vote or changed one registration,” said Judd Choate, president of the U.S. National Association of State Election Directors.

Homeland Security officials have said that in most of the 21 states only preliminary activity was observed from hackers and a small number of networks were compromised. Some states had complained in June they had no idea if Russians had attempted to infiltrate their systems.

California Secretary of State Alex Padilla said Friday that hackers had scanned state election systems but not breached the system. “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,” he said.

Homeland Security spokesman Scott McConnell said in a statement the government believes “officials should be kept informed about cybersecurity risks to election infrastructure” but also wants to protect “the integrity of investigations and the confidentiality of system owners.”

U.S. intelligence agencies have concluded the Kremlin orchestrated an operation that included hacking and online propaganda intended to help Trump win, Reuters reported in August.

Senator Mark Warner, a Virginia Democrat who co-chairs the Senate Cybersecurity Caucus, said Friday in a statement it is “unacceptable that it took almost a year after the election to notify states that their elections systems were targeted.”