Ukrainian President Petro Poroshenko spoke in favor of introducing martial law in Ukraine against the background of Russia's outright aggression against Ukrainian ships, UNIAN reported.

The Commander-in-Chief of the Armed Forces of Ukraine issued an order to bring the Armed Forces of Ukraine into full combat readiness. 

On Sunday Russia blocked the Kerch Strait for Ukrainian vessels – two small-sized ‘Berdiansk’ and 'Nikopol' armored artillery boats and the ‘Yany Kapu’ tugboat.