The U.S. and Russian defense chiefs spoke by telephone on Tuesday in a rare instance of communication between the two powers as tensions rise after Moscow blamed Washington for a deadly Ukraine attack over the weekend on Russian-annexed Crimea.

The two sides gave widely divergent accounts of the conversation — the first one between U.S. Defense Secretary Lloyd Austin and Russia's new Defense Minister Andrei Belousov, who replaced Sergei Shoigu in May.

The Pentagon said Austin and Belousov discussed the importance of open lines of communication.