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US Defence Secretary Lloyd Austin urged Russian Defence Minister Sergei Shoigu on Friday to move immediately to implement a ceasefire in Ukraine.
It was their first conversation since before the war began, the Pentagon said.
“Secretary Austin urged an immediate ceasefire in Ukraine and emphasised the importance of maintaining lines of communication,” it in a statement.
It is the first time Mr Austin has spoken with Mr Shoigu since February 18, six days before Russian forces invaded Ukraine, said Pentagon spokesman John Kirby.
The call came as the two sides battle along a long front line in eastern and southern Ukraine, with the Pentagon maintaining that Russia is weeks behind goals set in its war plan.
But Moscow has shown no indication of pulling back and is believed by western intelligence to want to take control of a swathe of southern Ukraine stretching along the Black Sea to Moldova.
The call also came as Finland and Sweden have expressed the desire to join Nato, a direct consequence of Russia's attack on Ukraine, which is not part of the defence alliance.