>> reporter: and carr actually believes this operation may have had a role in deterring russia from mounting destructive cyber attacks against ukraine. experts thought they would shut down the power grid, turn down the cell phone networks. that hasn't happened and this expert believes ukrainian hackers are playing a role in preventing that. >> the ukrainian people continue to amaze and surprise and impress. thank you. any minute president biden is set to get a briefing in poland on the humanitarian response to the crisis in ukraine. tomorrow the president is expected to meet with some of the refugees himself, all after plans to welcome 100,000 ukrainians to the united states. with me congressman allred, a member of the house.