The United States plans to announce $250 million in aid on Friday to shore up Ukraine's energy infrastructure in the face of Russian attacks and $300 million for Moldova, partly to help Chisinau wean itself from energy dependence on Russia.

The aid, described in draft documents seen by Reuters, is expected to be announced by U.S. Agency for International Development Administrator Samantha Power on the anniversary of Russia's invasion of Ukraine.

Tens of thousands of Ukrainian civilians and soldiers on both sides have been killed and millions have fled their homes since Russia launched its invasion of Ukraine on Feb. 24, 2022, triggering Europe's biggest land war since World War Two.

Russia, which failed to secure a quick victory in what it calls a "special operation" to demilitarize and "denazify" its neighbor, has repeatedly attacked Ukrainian energy infrastructure in what Western officials see as an effort to weaken Ukrainian morale in the grinding ground war.

"The United States government remains committed to helping the Ukrainian government maintain the stability and operation of its electricity system amid relentless and brutal attacks on critical infrastructure by Russian forces," said one draft document that described the $250 million in aid for Ukraine.

The $300 million for Moldova includes $80 million in budget support to offset high electricity prices, $135 million for electric power generation projects and $85 million to improve its ability to obtain energy supplies from alternative sources, according to a second draft document.

"This assistance will help Moldova address urgent needs created by (Russian President Vladimir) Putin's war, while also building toward long-term energy resilience and stronger interconnections with Europe," the second document said.

Moldova, a former Soviet republic of 2.5 million people neighboring Ukraine to the west, is one of the poorest nations in Europe and has traditionally been heavily reliant on Russian gas.

The money is from a pool of $45 billion for Ukraine included in a broader spending bill passed by Congress last year. Under U.S. budget procedures, Congress has 15 days after notification by the administration to review the planned spending. (Reporting By Arshad Mohammed; Additional reporting by Daphne Psaledakis and Patricia Zengerle; Editing by William Mallard)