Biden, Zelenskyy to sign US-Ukraine security agreement at G7 summit

"We'll be sending Russia a signal of our resolve," an official said.

A U.S. official tells me this is an "executive agreement," which means a future president could withdraw from it.

The official told me negotiations on this bilateral agreement started last fall, but the U.S. was not able to complete negotiations while waiting for Congress to pass the supplemental funding for Ukraine. Once that was passed, negotiations were accelerated.

The agreement states that the U.S. intends to work with Congress over the coming months to find a path to sustainable resources for Ukraine.

The agreement does not include any commitment to use U.S. forces to defend Ukraine. It will outline a vision of how the U.S. and its allies will work with Ukraine to strengthen its defenses and deter future aggression from Russia.

The pledge will be similar to bilateral agreements that Ukraine has already signed with more than a dozen other countries.

"If Vladimir Putin thinks he can outlast the coalition supporting Ukraine, he's wrong," Sullivan added. "He cannot just wait us out."

Zelenskyy and Biden will meet Thursday on the sidelines of the G7 and will hold a joint news conference.