The National Security Council says that Russia is attempting a “false flag operation” to “justify any attacks against civilian ships in the Black Sea and to then blame them on Ukraine.”

The declaration comes days after Russia backed out of a deal that helped move grain from Ukrainian ports, threatening global food supply.

NSC spokesperson John Kirby told reporters in a briefing Thursday afternoon that Russia may try to expand its targets in the Black Sea to attacks on civilian ships that are transporting grain and food.

“Russia has already announced publicly that all ships proceeding to Ukrainian ports in Black Sea waters will be considered potential carriers of military cargo, even though they are simply trying to pick up grain and food to be able to feed people around the world,” Kirby said.

Kirby said Russia is falsely trying to blame Ukraine for sea mines that Russia itself planted, releasing a video of a detonation it claimed was from a Ukrainian mine.

Kirby said the U.S. found it important to declassify and publicly share the information to warn that the Black Sea waters “are now more dangerous than they were before for civilian shipping and that’s because of one party and one party only: and that’s Russia.”