The playfor and sex videoUnited States sees evidence that hackers, possibly working for foreign governments, are snooping on the presidential candidates, the nation's intelligence chief said Wednesday. Government officials are working with the campaigns to tighten security as the race for the White House intensifies.

The activity follows a pattern set in the past two presidential elections. Hacking was rampant in 2008, according to U.S. intelligence officials, and both President Barack Obama and Mitt Romney were targets of Chinese cyberattacks four years later. Despite that history, cyber experts say neither Donald Trump's nor Hillary Clinton's campaign networks are secure enough to eliminate the risk.

"We've already had some indications" of hacking, James Clapper, director of national intelligence, said Wednesday at a cybersecurity event at the Bipartisan Policy Center in Washington. He said the FBI and the Department of Homeland Security were helping educate the campaigns.

Of the attacks, Clapper predicted, "we'll probably have more."

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The revelation comes after Clapper's office released a document earlier this month saying foreign intelligence services tracked the 2008 presidential election cycle "like no other." The document was part of a slideshow used to warn incoming Obama administration officials that their new jobs could make them prey for foreign spies.

Eight years ago, foreign intelligence services "met with campaign contacts and staff, used human source networks for policy insights, exploited technology to get otherwise sensitive data, engaged in perception management to influence policy," the document said. "This exceeded traditional lobbying and public diplomacy."

Some threats are publicly known.

Several weeks ago, the international group of activists and hackers known as Anonymous declared cyberwar on Donald Trump, urging supporters to take down his website and expose private information. A masked figure appeared on YouTube, saying, "Dear Donald Trump, we have been watching you for a long time and what we see is deeply disturbing."

The New York billionaire probably has the largest "attack surface" of all of the candidates, said John Dickson, a partner in the Denim Group, a San Antonio developer of secure software. "If it's the Bernie Sanders campaign, it's probably one website. If it's Donald Trump, it's his entire empire."

The Clinton and Trump campaigns didn't respond to questions about cybersecurity.

For its part, the U.S. was revealed to be snooping on the leaders of 35 nations, many of them allies, in the 2013 intelligence leaks by Edward Snowden. 

Dickson said the campaigns focused more on computer security because of the investigation into Clinton's use of a private email server while she was secretary of state, and a computer breach of voter data at the Democratic National Committee.

V. Newton Miller, chief executive officer of the Milwaukee-based PKWARE, which provides encryption software and advises federal agencies on data security, said foreign spying on campaign sites was inevitable.

"These campaigns are not working on encrypted platforms," he said. "It's a matter of when and how serious of an impact it is going to have on this election."

Additional reporting by Mashable.

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