US Secretary of State Antony Blinken was trying to send a message of defiance and hope when he took to the stage of a Kyiv bar on Tuesday night for a guitar performance of "Rockin' in the Free World".
But some Ukrainians have reacted angrily, chastising Washington's top diplomat for an ill-judged jam session in the capital while Ukrainian troops are fighting in trenches, struggling to hold back a Russian advance amid a shortage of weapons.
"One word is enough to describe US Secretary of State Antony Blinken's evening in Kyiv yesterday: inappropriate," said Svitlana Matviyenko, head of the Agency for Legislative Initiatives NGO.
Blinken is on a surprise trip to Kyiv weeks after Washington approved a $61 billion package of aid for the country following months of delays in Congress.
In a speech earlier on Tuesday he said the United States would back Ukraine until its security was "guaranteed".
A guitar player who has launched a musical diplomacy initiative at the State Department, Blinken later joined Ukrainian musicians at a famed Kyiv bar, Barman Dictat, for a rendition of Neil Young's 1989 "Rockin' in the Free World".
"I know this is a really, really difficult time. Your soldiers, your citizens, particularly in the northeast in Kharkiv are suffering tremendously," he said on stage, holding a red electric guitar.
"But they need to know, you need to know, the Untied States is with you... They're fighting not just for a free Ukraine but for the free world," he added.
Ukrainian lawmaker Bogdan Yaremenko, a former diplomat and MP from President Volodymyr Zelensky's party, said the performance was ill-timed, coming after delays to US aid cost Ukraine lives and territory.
"The message is not hard to understand, but it's not getting through," he said in a Facebook post.
Images of Blinken's performance sparked an angry backlash on social media.
"With all due respect, it's a mistake. The message is wrong," said Valeriy Chaly, Ukraine's ambassador to the United States from 2015 to 2019.