Ukrainian President Volodymyr Zelensky discussed specific defensive support with US President Joe Biden in an hour-long call on Wednesday, Zelenskiy wrote on Twitter.
The two leaders also discussed a new package of enhanced sanctions against Russia, Zelenskiy said, as well as financial and humanitarian aid support for Ukraine.
Also Wednesday, Slovakia has ordered Russia's embassy to cut its staff by 35, a foreign ministry spokesperson said, citing unacceptable activity by another Russian diplomat.
The aim of the move is to "set a maximum number of diplomatic and service passport holders at this (Russian) mission," Juraj Tomaga said in a statement.
On March 14, Slovakia expelled three Russian embassy staff based on secret service information.
This is a developing story.