Microsoft said Friday that hackers linked to the Iranian government targeted an undisclosed U.S. presidential campaign, as well as government officials, media targets and prominent expatriate Iranians.

“Microsoft’s claims that a presidential campaign was targeted is yet more evidence that our adversaries are looking to undermine our democratic institutions.”

Overall, the hackers attempted to penetrate 241 accounts — four successfully — though none of those penetrated was associated with presidential campaigns of current or past U.S. officials, Microsoft said. A company spokeswoman declined to identify those targeted, citing customer privacy.

The announcement is the latest sign that foreign governments are looking for ways to potentially disrupt the 2020 presidential election. U.S. intelligence officials have sounded the alarm about the risks for months.

Russia’s hacking of the Democratic National Committee and the Clinton campaign, as well as the subsequent leaks of emails during the 2016 election roiled the DNC, hurt the Clinton campaign and was a focal point in special counsel Robert Mueller’s probe.

Foreign hackers have long targeted U.S. government and politicians, generally with little notice. But the disruption caused by Russia’s attack has heightened awareness and prompted fears that other nations will try to follow Russia’s example. Iran in particular could have a stake in the outcome of the U.S. election after President Donald Trump withdrew the United States from a nuclear agreement and stepped up sanctions against the country.

The U.S. Department of Homeland Security said it was working with Microsoft to “assess and mitigate impacts.” Chris Krebs, director of the department’s Cybersecurity and Infrastructure Security Agency, said much of the activity is likely “run-of-the-mill” foreign intelligence service work.

But, “Microsoft’s claims that a presidential campaign was targeted is yet more evidence that our adversaries are looking to undermine our democratic institutions,” Krebs said.

Update

A late-breaking Reuters report said sources familiar with the operation said it was President Donald Trump’s reelection campaign that was targeted. However, Trump campaign Director of Communications Tim Murtaugh said, “We have no indication that any of our campaign infrastructure was targeted.”

The U.S. has been targeted numerous times in the past by Iranian hackers, particularly after the federal government imposes new sanctions on them.

© The Associated Press. All rights reserved.