Russia and Belarus have launched a long-planned joint military exercise involving thousands of troops that has raised concern in the West.

The defense minister of Belarus says the country closely allied with Russia will put forth a new military doctrine that for the first time provides for the use of nuclear weapons.

Russia and Belarus signed a deal formalizing the deployment of Moscow’s tactical nuclear weapons on the territory of its ally, although control of the weapons remains in the Kremlin.

Belarus’ authoritarian president says he has no intention of sending troops to Syria to serve alongside Russian forces in the country but is holding the door open for a potential deployment of military medics there.

Belarus is planning to deploy up to 200 troops to Syria to serve alongside Russian forces in the country.