Top US General Mark Milley spoke by telephone with his Russian counterpart General Valery Gerasimov, the Pentagon said, amid US warnings that Russia is poised to potentially invade Ukraine.
Milley, the chairman of the Joint Chiefs of Staff, and Gerasimov, chief of the Russian General Staff, "discussed several security-related issues of concern," said Colonel Dave Butler, the Joint Staff spokesman said on Friday.
"In accordance with past practice, both have agreed to keep the specific details of their conversation private," Butler said.
The telephone call is not the first between the two generals but their conversations are rare.
They last spoke on November 23, and discussed Russian troop movements around Ukraine.
The pair met in Finland in September and discussed ways to prevent military incidents between the two countries, according to Moscow.
Butler said Milley also held telephone calls on Friday with counterparts in France, Canada, Germany, Italy, Poland, Romania and Britain.
"The military leaders discussed items of mutual security concern, including ongoing coordination during the adjustment of US force posture in Europe," he said.
The United States announced Friday it is sending 3,000 more troops to Poland to reassure NATO allies amid heightened fears of a Russian invasion of Ukraine.
READ MORE: US to send extra 3,000 troops to Poland amid Ukraine-Russia crisis
Blinken-Kuleba phone call
The United States on Friday promised "robust" support for Ukraine in the face of what Washington called "an increasingly acute threat of possible further Russian aggression."
Secretary of State Antony Blinken spoke by phone with his Ukrainian counterpart Dmytro Kuleba and "reinforced that Ukraine continues to have the United States’ enduring and steadfast support for its sovereignty and territorial integrity," the State Department said.
US National Security Advisor Jake Sullivan warned that a Russian invasion could come "any time," though he acknowledged it was unclear whether Russian President Vladimir Putin had made the decision to invade.
Echoing the alarm, President Joe Biden urged Americans to leave Ukraine immediately.
During his call with Kuleba, Blinken underscored that "any and all aggression against Ukraine by Russia will be met with swift, severe, and united consequences."
Putin to talk to Biden, Macron
US President Joe Biden and Russian President Vladimir Putin will speak on Saturday, a White House official said, after Washington said earlier on Friday that Russia has massed enough troops near Ukraine to launch a major invasion.
"They will be speaking Saturday morning. Russia proposed a call Monday. We counter-proposed Saturday, and they accepted," the official told Reuters.
Biden has said the US military will not enter a war in Ukraine, but he has promised severe economic sanctions against Moscow, in concert with international allies.
Putin will also speak with French President Emmanuel Macron on the same day, TASS quoted Peskov as saying on Friday.
READ MORE: Biden: US citizens should leave Ukraine immediately