WASHINGTON – U.S. intelligence officials accused China and Russia on Thursday of systematically stealing American high-tech data for their own national economic gain.

It was the most forceful and detailed public airing of U.S. allegations after years of private complaints. U.S. officials and cybersecurity experts said the U.S. must openly confront China and Russia in a broad diplomatic push to combat cyberattacks that are on the rise and represent a “persistent threat to U.S. economic security.” But experts said solving the problem isn’t easy.

In a report released Thursday, U.S. intelligence agencies said “the governments of China and Russia will remain aggressive and capable collectors of sensitive U.S. economic information and technologies, particularly in cyberspace.”

Speaking at a forum at the National Press Club, Robert Bryant, the national counterintelligence executive, said the U.S. is finally making the charges public because China and Russia are stealing sensitive U.S. technology data.

If Russia and China build their economies on stolen U.S. data, “that’s not right,” Bryant said. “We want to basically point out what the issue is.”