MOSCOW — In a solemn ceremony at an airport in Ukraine on Sunday, President Volodymyr Zelensky paid his respects to the 11 citizens from his country who were killed when Iran’s military mistakenly shot down a passenger jet in Tehran this month.

Mr. Zelensky has grappled with the diplomacy around the downing of the plane, Ukraine International Airlines Flight 752. The missile strike put his government in the middle of a conflict between the United States and Iran, and he has walked a fine line as his country sought answers from Tehran.

On the morning of the crash, Iranian air defenses had been on high alert after Tehran launched ballistic missiles at two American bases in Iraq in response to the United States’ killing of a top Iranian general in Baghdad. Iran was anticipating retaliation to its missile strikes on the bases.

Though the Ukrainian government quickly concluded that a missile had downed the plane, killing all 176 people aboard, it refrained from public criticism of Tehran until its investigative team on the ground had found irrefutable proof, including shrapnel holes in the plane’s fuselage.