UKRAINE and Russia traded accusations today over who was responsible for blowing up a major dam and hydroelectric power station.

This comes as Kiev began legal new proceedings against Moscow at the International Court of Justice in The Hague, Netherlands.

The Kakhovka dam on the Dnipro river, located in a part of southern Ukraine that Moscow controls, was breached on Tuesday which officials said could cause a possible “ecological disaster” due to flooding.

Officials from both sides in the war ordered hundreds of thousands of residents downriver to evacuate.

The Ukrainians accused Russian forces of destroying the dam while Russian officials countered that the facility had been damaged by Ukrainian military strikes in the contested area.

The fallout could cause the flooding of homes, streets and businesses downstream and could deplete water levels upstream that help cool Europe’s largest nuclear power plant at Zaporizhzhya.

The damage could also drain supplies of drinking water to the south in Crimea.

The breached dam added a complex new element to Russia’s ongoing war in Ukraine, now in its 16th month. 

Ukrainian forces were widely seen to be moving forward with a long-anticipated counteroffensive in patches along more than 620 miles of front line in the east and south of Ukraine.

Ukraine’s nuclear operator Energoatom said in a statement that the situation is “controllable.”

The United Nations International Atomic Energy Agency posted on Twitter that its experts were closely monitoring the situation at the plant and there was “no immediate nuclear safety risk” at the facility.

Ukrainian authorities have previously warned that the dam’s failure could unleash 4.8 billion gallons of water and flood Kherson and dozens of other areas where hundreds of thousands of people live.

Top Ukrainian diplomat Anton Korynevych called Russia a “terrorist state” today as he opened his country’s case against Moscow at the International Court of Justice (ICJ), and lawyers argued that Russia bankrolled a “campaign of intimidation and terror” by rebels in eastern Ukraine in 2014.

The case is being brought by Kiev against Russia, linked to Moscow’s 2014 annexation of the Crimean peninsula and the arming of rebels in eastern Ukraine.

Ukraine wants the ICJ to order Moscow to pay reparations for attacks in the regions, including for the downing of Malaysia Airlines flight MH17 that was shot down by Russian-backed rebels on July 17 2014, killing all 298 passengers and crew.

Russia has always denied any involvement in the incident.

The case is one of several legal proceedings against Russia linked to Ukraine.