Washington has said it would continue to support Ukraine amid concerns in Kyiv and among its Western allies over tens of thousands of Russian troops amassed on its border. Russia denies planning a military offensive.
"The second bird in Kyiv! More than 80 tons of weapons to strengthen Ukraine's defense capabilities from our friends in the USA! And this is not the end," Reznikov wrote on Twitter.
About 90 tonnes of "lethal security assistance," including ammunition, from the package approved by the U.S. in December arrived in the Ukrainian capital on Saturday.
(Reporting by Natalia Zinets; Editing by Alexander Smith)