The commander of U.S. forces in Europe called for bolstering Ukraine's defenses against Russian aggression, in eastern Ukraine as well as in the Black Sea.
General Curtis Scaparrotti made the comments on March 5 in testimony before the U.S. Senate Armed Services Committee.
Scaparrotti spoke just over three months after Russian naval forces seized three Ukrainian vessels operating in the Kerch Strait, near Crimea and the Sea of Azov. A total of 24 Ukrainian sailors were also detained.
Russia has insisted Ukrainian vessels were illegally crossing maritime borders.
Scaparrotti, who is also the top commander of NATO, said the United States has already sold Javelin anti-tank missiles to Ukraine.
But he told senators there were other things -- "like sniper systems, ammunition"-- that Washington could provide to strengthen Ukraine's forces.
He also said Washington might consider boosting naval defenses in the Black Sea, though he did not specify how.
Moscow "continues to arm, train," and even "fight alongside antigovernment forces in eastern Ukraine," Scaparrotti said. He also accused Moscow of violating the 2015 Minsk agreement designed to end the conflict.