Saboteurs, spies and thieves are expanding their computer attacks against a vulnerable American Internet infrastructure, chipping away at U.S. wealth and security over time, according to the latest U.S. intelligence appraisal of the top dangers facing the country.

In its annual worldwide threats assessment released Thursday, the Office of the Director of National Intelligence says that a catastrophic destruction of infrastructure is unlikely, but it nonetheless placed cyber attacks above terrorism on the list of dangers facing the nation.

“Cyber threats to U.S. national and economic security are increasing in frequency, scale, sophistication, and severity of impact,” the assessment says. “Rather than a ‘Cyber Armageddon’ scenario that debilitates the entire US infrastructure, we envision something different,” it said. “We foresee an ongoing series of low-to-moderate level cyber attacks from a variety of sources over time, which will impose cumulative costs on U.S. economic competitiveness and national security.

Russia, China, Iran and North Korea are the top nation state cyber threats, the intelligence assessment found.

The assessment said officials are increasingly concerned that cyber attackers will seek to change or destroy crucial data in a way that could undermine financial markets and business confidence.

More broadly, the assessment surveyed an increasingly uncertain world, with more terrorist safe havens than at any time in recent history.

“Unpredictable instability is the new normal,” James Clapper, director of national intelligence, told the Senate Armed Services Committee.

(AP)