Defense Secretary Lloyd Austin has ordered the deployment of additional troops and military assets to various parts of Europe amid the Ukraine crisis to further support US NATO allies, a senior Pentagon official said, CNN reported.

According to the official, the defense ministry will send a total of 500 troops. The deployment will include sending KC-135 refueling planes to Greece, but he did not say how many planes would be sent or where they would come from.

The official said an operational air support center would be deployed to Poland and Romania, while an artillery company and a repair company would be deployed to Germany.

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.

With this additional deployment, about 100,000 US troops are now stationed in Europe, either on a rotational or permanent basis, the official said.