The director of national intelligence on Wednesday said officials had seen signs of attempted cyberattacks on 2016 presidential campaigns.

“We’ve already had some indications of that,” James R. Clapper Jr. said at a cyber-event at the Bipartisan Policy Center in Washington.

He did not indicate whether the attempted intrusions were successful or whether they were by foreign or domestic hackers. Nor did he specify whether the websites or campaign networks of Democratic candidates Hillary Clinton and Bernie Sanders or Republican presumptive nominee Donald Trump were targeted.

“We’re aware that campaigns and related organizations and individuals are targeted by actors with a variety of motivations — from philosophical differences to espionage — and capabilities — from defacements to intrusions,” said Brian P. Hale, director of public affairs for the Office of the Director of National Intelligence. “We defer to FBI for specific incidents.”

In 2008, Chinese hackers compromised the computer networks of Sens. Barack Obama (D-Ill.) and John McCain (R-Ariz.). In 2012, foreign and domestic hackers tried to gain access to the campaign networks of Obama and Mitt Romney (R).

The U.S. government and American businesses have become constant targets for hackers. In 2013, federal agents notified more than 3,000 U.S. companies that their computer systems had been hacked in the previous year. The Pentagon reportedly sees millions of attempts a day.

Clapper said the Department of Homeland Security and the FBI are working “to educate campaigns against potential cyberthreats.”

He added: “I anticipate as the campaigns intensify, we’ll probably have more of those [attempts].”