Days after Russia suspended participation in a wartime deal that allowed grain to flow from Ukraine to countries around the world, the White House on Wednesday warned that the Russian military is preparing for possible attacks on civilian shipping vessels in the Black Sea.

Since leaving the Black Sea Grain Deal this week, Russia has already struck Ukraine’s grain export ports in Odesa with missile and drone attacks. Some 60,000 tons of grain were destroyed in the attacks.

“Our information indicates that Russia laid additional sea mines in the approaches to Ukrainian ports,” White House National Security Council spokesman Adam Hodge said in a statement. “We believe that this is a coordinated effort to justify any attacks against civilian ships in the Black Sea and lay blame on Ukraine for these attacks.”

The Russian Defense Ministry has declared international waters in northwestern and southeastern parts of the Black Sea “temporarily dangerous” for shipping. That followed Ukraine’s pledge to continue grain shipments despite the Russian pullout from the deal.

The ministry warned it will see any incoming vessel as laden with military cargo.