A damaged military vehicle as civilians are evacuated along humanitarian corridors from the Ukrainian city of Mariupol under the control of Russian military and pro-Russian separatists, on March 21, 2022.A damaged military vehicle as civilians are evacuated along humanitarian corridors from the Ukrainian city of Mariupol under the control of Russian military and pro-Russian separatists, on March 21, 2022.

The NATO alliance estimates that up to 40,000 Russian troops have been killed, injured, captured or gone missing during the first month of the war in Ukraine.

The official, who spoke on the condition of anonymity in order to share the alliance's latest intelligence assessment of the ongoing war, said between 7,000 and 15,000 Russian troops have died.

Russian officials have previously refused to reveal how many of their troops have died. On Tuesday, the Kremlin spokesman said that the Ministry of Defense in Russia has the exclusive right to reveal such figures.

We did not have the authority to speak about the numbers during the special military operation, Peskov said.

The number of Russian troops that have been removed from battle has been denied by the Pentagon.

Up to 4,000 Russian troops have been killed in the war in Ukraine, according to the U.S. intelligence community.

The figure was presented to lawmakers by the director of the Defense Intelligence Agency.

Between 2,000 and 4,000 is the low confidence range. During testimony before the House Intelligence Committee, Berrier said that the number came from some intelligence sources and also open sources.

FBI Director Christopher Wray, NSA Director Gen. Paul Nakasone, Director of National Intelligence Avril Haines, CIA Director William Burns and DIA Director Lt. Gen. Scott Berrier testify before the House Permanent Select Committee on Intelligence in the Rayburn House Office Building on Capitol Hill on Tuesday, March 8, 2022 in Washington, DC.

NATO Secretary-General Jens Stoltenberg said earlier in the day that the alliance would approve a major increase of its forces.

The alliance is likely to deploy four new battle groups in Bulgaria, Hungary, Romania and Slovakia.

NATO will be strengthened with major increases in the eastern part of the alliance, according to NATO Secretary General Jens Stoltenberg.

There is a developing story. You can check back for updates.