Polish Foreign Minister Radosław Sikorski has arrived in Kyiv

On the morning of September 11, Polish Foreign Minister Radosław Sikorski arrived in the Ukrainian capital.
According to Censor.NET, the Polish foreign minister announced this on X.
"Good morning from Kyiv," Sikorski wrote.
At this time, his plans and the purpose of his visit are unknown.
What led up to this?
A few days ago, Sikorski compared Russia’s attacks on Ukrainian cities to Nazi Germany’s bombing of London.