Ukraine’s president, Volodymyr Zelensky, is making a rare trip to Washington this week, pleading his case for American military aid, something which has long been a lifeline for his country but is now increasingly in doubt.Julian Barnes, who covers international security for The Times, explains what has brought Ukraine to the most perilous point since the war began nearly two years ago.Guest: Julian E. Barnes, a correspondent covering the U.S. intelligence agencies and international security for The New York Times.Background reading: The U.S. and Ukraine are searching for a new strategy after a failed counteroffensive.The Ukrainian leader will be appealing for more military support from the United States as an emboldened Russia steps up its attacks on his country.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.