A senior U.S. defense official said more than 70 M-777 howitzers have arrived in Ukraine. The U.S. has committed to giving the country 90 artillery pieces. Russia's State Duma speaker said on Monday that countries supplying weapons to Ukraine are "inciting a catastrophe." He said the leaders of European states, led by Germany, have become a party in the conflict. The move to supply weapons has also raised concern among some U.S. scholars.