KYIV, Ukraine—A year into Russia’s full-scale invasion, Ukrainian Finance Minister Sergii Marchenko is steadily gathering enough financial aid from the U.S. and other international allies to ensure the Ukrainian state can keep functioning. His new challenge is to assuage doubts about the country’s history of corruption. Graft scandals at the Ukrainian Defense Ministry and other government agencies have added to calls in the U.S. for stricter controls over assistance for Ukraine, as more American voters and lawmakers are growing skeptical about the cost of financial and military support for the country’s defense against Russia’s invasion.

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