The top U.S. intelligence official warned Congress of an alarming rise in cyberattacks at a hearing on global threats Thursday.

Director of National Intelligence Avril Haines said the number of ransomware attacks worldwide grew as much as 74% in 2023.

The comments from Haines come as various companies, such as UnitedHealth GroupMGM Resorts and Clorox, have been disrupted by cyberattacks in the past year.

“Although the likelihood of any single attack having a widespread effect on interrupting critical services remains low, the increased number of attacks and the actors’ willingness to access and manipulate these control systems increases the collective odds that at least one could have a more significant impact,” Haines told members of the Senate Armed Services Committee.

Haines said U.S. entities were the most heavily targeted in 2023 with attacks in sectors such as healthcare doubling from the prior year.

The intelligence chief also said they have seen a large increase in attacks on control systems for critical infrastructure but added that there are several ways for entities to prevent being targeted.