This was stated by the President of Ukraine Volodymyr Zelensky in a video message.

De facto, we have already made our way to NATO.
De facto, we have already proven compatibility with Alliance standards. They are real for Ukraine – real on the battlefield and in all aspects of our interaction.
We trust each other, we help each other, and we protect each other. This is the Alliance.
De facto. Today, Ukraine is applying to make it de jure. In a process that is consistent with our value in protecting our entire community. In an expedited manner.
We are taking our decisive step by signing Ukraine’s application for accelerated membership to NATO.

NATO Secretary General Jens Stoltenberg’s press conference is expected at 19:00.