WASHINGTON - The Biden administration's next security assistance package for Ukraine is expected to include munitions and vehicles but not significant new capabilities or counter-air defenses, two U.S. officials briefed on the $725 million package told Reuters on Friday.

The package, that could come as soon as Friday, is the first aid package since Russia's barrage of rocket attacks on civilian population centers in Ukraine in recent days.

The officials, speaking on the condition of anonymity, said that the timing of the announcement of the weapons package as well as its contents and value could change until the last minute.

One of the officials said that while the aid package was not expected to include material to defeat missile attacks like the ones seen over the last week, it was designed to bolster Ukraine's ability to beat back Russia in the counter offensive that has yielded large territorial gains in recent weeks.

Separately, Ukraine expects the United States and Germany to deliver sophisticated anti-aircraft systems this month to help it counter attacks by Russian missiles and kamikaze drones, Defense Minister Oleksiy Reznikov said on Friday.

The munitions and vehicles will be sent using Presidential Drawdown Authority (PDA) allowing them to be shipped to Ukraine in the coming days.

Presidential Drawdown Authority allows the United States to transfer defense articles and services from stocks quickly without congressional approval in response to an emergency.

This is the second PDA package of the U.S. government's 2023 fiscal year which is currently functioning under a stop-gap funding measure and allows President Joe Biden to tap up to $3.7 billion in surplus weapons for transfer to Ukraine through mid-December.

In general, to finance weapons for Ukraine, including the sophisticated anti-aircraft NASAMS systems expected this month, Washington uses funds from the Ukraine Security Assistance Initiative (USAI) to procure weapons from industry, rather than pulling them from existing U.S. weapons stocks.

NASAMS are made by Raytheon Technologies Corp and Norway's Kongsberg.

The White House declined to comment on the package.

The latest package would bring a total of more than $17.5 billion worth of U.S. security assistance since Russia invaded Ukraine on Feb. 24.

(Reporting by Mike Stone and Humeyra Pamukin, Washington Editing by Tomasz Janowski)