Zelensky's U.S. visit leaves unanswered questions

Ukraine's President Volodymyr Zelenskiy addresses a joint meeting of the U.S. Congress while U.S. House Speaker Nancy Pelosi (D-CA) and U.S. Vice President Kamala Harris look on, as a U.S. flag and Ukrainian flag are pictured on the table, in the House Chamber of the U.S. Capitol in Washington, U.S., December 21, 2022. REUTERS/Evelyn Hockstein

For President Volodymyr Zelenskiy, his surprise visit to Washington this week was a clear success: he returns to Europe with new financial and military commitments from the United States and bipartisan support for Ukraine's war with Russia.

But the visit also leaves several key questions unanswered, including how U.S. military support could evolve, whether Congressional support for the war will endure and - crucially - how the war will end.