Picture used for illustrative purposes only.

NATO allies have put forces on standby and dispatched ships and fighter jets to bolster eastern European defences as tensions rise over Russia's military buildup around Ukraine, the alliance said Monday.

"NATO will continue to take all necessary measures to protect and defend all Allies, including by reinforcing the eastern part of the Alliance. We will always respond to any deterioration of our security environment," NATO Secretary General Jens Stoltenberg said in a statement.

READ MORE

Burkina Faso President Kabore detained at military camp

UAE intercepts Houthi ballistic missiles attack

The alliance pointed to decisions in recent days by Denmark to send a frigate and warplanes to the Baltics, Spain bolstering naval deployments and the Netherlands putting a "ship and land-based units on standby" for its rapid response force.

NATO will continue to take all necessary measures to protect and defend all Allies.

"I welcome allies contributing additional forces to NATO," Stoltenberg said in a statement. "NATO will continue to take all necessary measures to protect and defend all allies, including by reinforcing the eastern part of the alliance."

Ukraine is not in NATO, but some of its neighbours including Poland are.