Ukraine's President Volodymyr Zelensky has increasingly of late lashed out publicly at the proverbial hand that feeds him. He and his top officials have long complained that the billions in approved Western defense aid and shipments have been much too slow to reach Ukraine, giving the superior-armed Russians a clear advantage.

But now as things get more desperate especially in the Kharkiv region where Russian forces are fast advancing, Zelensky is going after President Biden himself. There's a major Ukraine-backed peace summit in Switzerland set for next month, and it's looking very unlikely that Biden will attend, leaving Zelensky deeply unhappy.

During a visit to Belgium on Tuesday, Zelensky told reporters that it would not be "a strong decision" if Biden failed to attend the summit, which is to take place June 15-16 outside Lucerne. He went so far as to say it would be tantamount to a standing ovation for Putin.