"Interception of radio and phone conversations by the Security Service of Ukraine irrefutably indicates that the given attack was organized by terrorists supported by Russia," he said.
According to the Head of State, the evidence is also Russia's blocking of the UN Security Council's statement and its silence on assessments of the terrorists' actions in Donetsk and Luhansk regions - regarding the attack on Volnovakha, shameful behavior with Ukrainian war prisoners and tragedy at the trolleybus stop in Donetsk.
"I consider it an issue of every country to determine its attitude to the tragedy in Mariupol and Volnovakha. Evasion of fair and honest assessments is also a support of terrorism, which is unacceptable," Petro Poroshenko noted.
He has also informed that the Security Service had seized the gun spotter involved in the attack on Mariupol. According to the President, he is currently giving evidence that will be published tomorrow. "The whole world must know the perpetrators of the given tragedy," the Head of State said.
The President has mentioned "professional and efficient actions of the Armed Forces of Ukraine in response of the attacks along the front line". Also, according to the Ministry of Defense, more than 700 militants, 8 Grad rocket systems, including 4 of 6 involved in the shelling of Mariupol, several vehicles with ammunition and 7 armored vehicles have been eliminated recently.
At the same time, the President expressed concern over the statement of terrorists' leaders on unilateral withdrawal from the Minsk agreements "that provide for de-escalation, border closure, liberation of illegally seized persons, withdrawal of heavy armament, ceasefire and have been recognized by the world community".
So, given the escalation of the situation, the NSDC will consider the emergency measures to counter the Russian threat and the support of terrorism in the territory of Ukraine, as well as to elaborate the strategy of actions in conditions of intensification of terrorist groups.
In this context, Petro Poroshenko has also informed on several negotiations on the support of Ukraine.
"We coordinate our actions with foreign partners. Numerous phone conversations with U.S. Vice President Joseph Biden, negotiations in Riyadh with President of France Francois Hollande, President of the European Council Donald Tusk, High Representative of the European Union for Foreign Affairs and Security Policy Federica Mogherini have resulted in the tomorrow's session of the Council of Foreign Ministers of the EU that will coordinate our further joint actions on the enhancement of Ukraine's security and the increase of pressure on Russia," he said.
Events in Mariupol are "the most dreadful tragedy since the beginning of the war", as stated by the President. According to him, if militants and Russia complied with the Minsk agreements, there would be no physical possibility of tragedies in Volnovakha and Mariupol.