When the U.S. said it had reached an agreement to eliminate the use of force in the Black Sea, it looked like a breakthrough. Then Russia listed its conditions.

For us, a ceasefire at sea means stopping attacks on Ukraine’s port infrastructure. That’s how we see it. What Russia means by it is, of course, not hard to guess,” Pletenchuk said. He added that conclusions should be drawn only after the final document is released.

The United States will evaluate demands made by Russia after Moscow had agreed "in principle" to a U.S.-brokered ceasefire with Ukraine in the Black Sea to allow safe navigation, U.S. Secretary of State Marco Rubio said on Wednesday.