WASHINGTON

Secretary of Defense Lloyd Austin has ordered the deployment of an additional 500 troops to Europe to bolster NATO's capabilities amid Russia's ongoing war on Ukraine, the Pentagon announced on Monday. 

Austin ordered the deployment over the weekend in order to "augment" forces that have already been deployed to Europe, a senior defense official told reporters on a background call.

"These additional forces are going to be positioned to respond to the current security environment in light of Russia's renewed aggression against Ukraine, and again, to reinforce deterrence and defensive capabilities of NATO, particularly the eastern flank," the official said, emphasizing that "as always, these are not permanent moves."

US President Joe Biden authorized in January the activation of some 8,500 troops to assist NATO forces, particularly in eastern Europe. So far, less than half that figure has been deployed. About 3,000 troops have been deployed to Poland, Germany and Romania.

The official said this weekend's authorization includes KC-130 refueling aircraft that will be sent to Suda Bay in Greece, an air support operations center that will be deployed in Romania and Poland, as well as ordinance and maintenance companies to Germany.

Russia's war on Ukraine, which began on Feb. 24 has drawn international condemnation, led to financial sanctions on Moscow, and spurred an exodus of global companies from Russia. The West has also imposed biting export restrictions on key technologies that are now prohibited from being sent to Russia.

At least 406 civilians have been killed and 801 others injured in Ukraine since the beginning of the war, according to UN figures. But the international body has maintained that conditions on the ground have made it "difficult to verify" the true number of civilian casualties.

More than 1.7 million people have also fled to neighboring countries, the UN Refugee Agency said.

*Kasim Ileri contributed to this report