A new $2.6 billion package of U.S. military aid to Ukraine includes $500 million for immediate supplies.

WASHINGTON — The United States plans to send Ukraine additional air defense interceptors and munitions as part of a $2.6 billion aid package, part of which will be used to help Kyiv prepare for a planned spring offensive against Russian troops.

The package announced on Tuesday includes $500 million in ammunition and equipment from U.S. military stockpiles, and $2.1 billion that the United States will use to buy munitions, radar and other weapons to send to Ukraine in the future.

“Russia alone could end its war today,” Secretary of State Antony J. Blinken said in a statement. “Until Russia does, the United States and our allies and partners will stand united with Ukraine for as long as it takes.”

The $2.1 billion, which is being provided under the Ukraine Security Assistance Initiative, a funding program led by the Department of Defense, will be used to purchase missiles for NASAMS air defense systems. The money will also be used to purchase antiaircraft ammunition, mobile laser-guided rocket systems, fuel tankers and other equipment, according to the Pentagon.

The air defense systems in particular are notable as Russia continues to launch barrages of long-range missiles at Ukraine.

Meanwhile, a fierce battle still rages in the eastern city of Bakhmut, which is at the heart of a Russian campaign to seize all of the Donbas region of eastern Ukraine. Russian troops were expected to have taken the city months ago, but the battle has been long, costly and so far indecisive.