WASHINGTON, July 8 - The United States is sending to Ukraine up to $400 million in additional military equipment and supplies, including four more medium-range rocket systems and ammunition, as the embattled nation tries to repel Russia’s advances in the Donbas region, the Defense News reported.

The four additional M142 High Mobility Artillery Rocket Systems, or HIMARS, will bring the total number sent to Ukraine to a dozen, a senior defense official told reporters in a briefing Friday. The official said the first eight HIMARS were particularly useful for Ukraine, as the fight in the Donbas has largely evolved into an artillery duel. The official refuted Russian reports that two of the delivered HIMARS were destroyed, and said all eight are accounted for and still in use by Ukraine.