Ukraine has barred all Russian men between the ages of 16 and 60 from entering the country, officials announced Friday. Ukraine’s parliament voted Monday to impose martial law in the country for 30 days after Russian forces rammed into and opened fired on three Ukrainian navy vessels in the Azov Sea. Petro Tsygykal, chief of the Ukrainian Border Guard Service, announced that no Russian adult males will be allowed to cross into Ukraine while martial law is in place. President Petro Poroshenko said the measure was taken “in order to prevent the Russian Federation from forming private armies” on Ukrainian soil. President Donald Trump scrapped a meeting with Russian leader Vladimir Putin scheduled for Saturday in Argentina over the dispute, saying it isn’t appropriate to meet Putin since Russia hasn’t released its Ukrainian captives from the incident.