The Washington Post writes about this, citing sources in the US administration.

Burns secretly visited the Ukrainian capital late last week to brief Volodymyr Zelensky on his assumptions about Russia's military plans in the coming weeks and months.

According to the publication, Burns and Zelensky during the meeting discussed the question of how long the Ukrainian authorities can count on continued financial and military assistance from Washington and other Western countries.

In December, Burns opined that the absence of peace talks on Ukraine is due to Russia's alleged unwillingness to hold them.