Russia’s Defense Ministry announced a Russian warship fired warning shots at a cargo ship in the Black Sea. The ministry said the Palau-flagged Sukru Okan vessel was heading north to the Ukrainian Danube River port of Izmail.

According to the ministry, Russian forces fired shots from automatic small arms to force it to stop after the ship’s captain failed to respond to a request to halt for an inspection.

Russia has said it would treat any ships approaching Ukrainian ports as potential military vessels after it left a U.N.-brokered deal that allowed Ukrainian grain a safe passage through the Black Sea.

Ukraine condemned Russia’s firing of warning shots at the cargo ship on Monday, Aug. 14, calling the move “provocative.”

“We call on the international community to take decisive action to prevent Russian Federation’s actions that impede the peaceful passage of vessels through the Black Sea,” Ukraine’s Ministry of Foreign Affairs said in a statement.

Ukrainian Deputy Prime Minister Oleksandr Kubrakov added “In order to avoid provocations, we recommend that masters of vessels sailing to/from Ukrainian seaports sail as close as possible to the coast of the northwestern part of the Black Sea, through the territorial waters of Turkey, Romania and Bulgaria.”

Ukraine’s condemnation of the Russian warning shots came the day Russia’s ruble hit its lowest value since the early weeks of the invasion. On Monday, the ruble hit 101.04 per U.S. dollar, meaning 1 ruble is worth less than a penny.

The ruble has lost around a quarter of its value since the invasion began. While the Bank of Russia has blamed the drop on a shrinking balance in trade, President Vladimir Putin’s economic adviser said it was due to loose monetary policy from the bank.

The warning shots and the drop in the ruble’s value comes amid a backdrop of attacks in southern Ukraine.

At least three people were wounded in two waves of Russian drone and missile attacks overnight Monday on the port city of Odesa. The attacks followed Russian shelling that killed seven people and wounded at least 22 in Ukraine’s southern region of Kherson.