A top U.S. senator is calling on the nation’s largest tech companies to do more to combat misinformation amid Russia’s ongoing invasion of Ukraine.

On Friday, U.S. Senator Mark Warner, D-Virginia, sent letters to AlphabetMetaRedditTelegramTikTok, and Twitter asking the companies to take further action to prevent Russian propaganda operations on their platforms. Warner—who is chairman of the U.S. Senate Select Committee on Intelligence—also pointed out that YouTube continues to allow Russian websites known for spreading propaganda to make money from ads.

Joshua Lowcock, global digital and brand safety officer at the IPG-owned agency Universal McCann, said ad-tech companies need to “stop funding with ad dollars and amplifying (via paid ads) Russian state-owned media which are currently waging a propaganda war.”

Read the article in Forbes.