Ukrainian commander-in-chief Ruslan Khomchak said on Tuesday Russia was building up armed forces near Ukraine's borders in a threat to the country's security.
On Thursday, Zelensky's ministers discussed the escalating security situation with Western allies including US Secretary of Defence Lloyd Austin. 'In this way, [Russia] seeks to create an atmosphere of threat and, at the same time, of pressure during the ceasefire negotiations and for peace as our value'.
The president also recently approved an additional $125 million worth of lethal aid to Ukraine to defend its borders with Russian Federation, including two armed patrol boats and counter-artillery radar. The State Department said Blinken expressed condolences for the losses.
Kirby said the Russian escalations include violations of a July 2020 ceasefire, brokered by the Organization for Security and Cooperation in Europe, that led to the deaths of four Ukrainian soldiers in the eastern part of the country on March 26 and the wounding of two others. Moscow says it only provides political and humanitarian support to the rebels and says Russians fighting in Ukraine are volunteers.
The Kremlin said Wednesday it was concerned about mounting tensions in eastern Ukraine and that it feared Kyiv's government forces could do something to restart a conflict with pro-Russian separatists.
"We obviously don't want to see any more violations of Ukrainian territory", he said.
A high-ranking Ukrainian government official, speaking on condition of anonymity, claimed that the Russian army was practising "military coordination" with separatists.
Khomchak denounced the "threat to the military security" of Ukraine by the Russian army, saying that some 28,000 separatist fighters and "more than 2,000 Russian military instructors and advisers" are now stationed in eastern Ukraine.
On Thursday, Kremlin spokesman Dmitry Peskov did not confirm the troop buildup on the border, saying Moscow was at liberty to move troops across its territory.
He added that "it should not worry anyone and does not pose a threat to anyone".
Both sides provided few details of the call between Chairman of the U.S. Joint Chiefs of Staff General Mark Milley and General Valery Gerasimov, the head of Russian's military general staff.
Canada, long one of Russia's harshest critics, said on Monday it was imposing sanctions against two Russians and four business entities in response to Moscow's "illegal occupation and annexation" of Crimea in 2014.
On Wednesday, the Pentagon said U.S. forces in Europe had raised their alert status following the "recent escalations of Russian aggression in eastern Ukraine".
On Thursday, the deputy head of Zelensky's office, Roman Mashovets, called for joint drills with North Atlantic Treaty Organisation forces to "help stabilise the security situation".