After weeks of Mr. Trump claiming he could leverage his relationship with the Russian leader to bring peace, Mr. Putin’s continued aggression has prompted even Mr. Trump to question whether he has been strung along.

Deal Maker or Duped? Trump’s Embrace of Putin Shows Few Results.

The American president’s preference for praising and excusing the Russian leader has yielded no progress toward peace in Ukraine.

By Zolan Kanno-Youngs and Luke Broadwater

Reporting from Washington