identify only key information from the text, summarize using bullet-points: WASHINGTON, May 25 (Reuters) - The United States plans to announce up to $300 million worth of military aid for Ukraine comprised mainly of ammunition, two official sources said on Thursday. The package could be announced as soon as Friday, but perhaps after the Memorial Day holiday weekend in the United States, said the sources, who spoke on condition of anonymity. The package was expected to contain more Guided Multiple Launch Rockets (GMLRS) for HIMARS launchers, and ammunition for Ukraine's defense against Russia. The equipment would be funded using Presidential Drawdown Authority, or PDA, in which the president can authorize the transfer of articles and services from U.S. stocks without congressional approval in response to an emergency. The U.S. has pledged more than $35 billion worth of security assistance to Ukraine since the Feb. 24, 2022, invasion by Russian forces. The Pentagon continues to work its way through an accounting error that overstated the value of past aid, an error that may lead the way for more weapons being sent to Ukraine.