Russian President Vladimir Putin on Wednesday announced partial military mobilisation as the Ukraine conflict reaches seven months, The Associated Press reported.

More than three lakh citizens, who have served in the Army, will be mobilised to help Russia in its war against Ukraine. Students and conscripts – those who have been drafted to join the Army – will not be mobilised.

“Mobilization measures will begin today, September 21,” Putin said, according to The Moscow Times. “Only those citizens currently in the reserve will be subject to a call-up for military service, first and foremost those who have served in the ranks of the Armed Forces.”

The announcement comes ten days after Moscow had announced that its troops were retreating from key areas in the eastern Kharkiv region after a counterattack by Ukrainian forces.

Media reports said that this was Moscow’s worst defeat since its troops were forced back from Ukraine’s capital, Kyiv, in March.

Russia’s invaded Ukraine on February 24. The Kremlin described its actions as a “special operation” to demilitarise and “de-Nazify” Ukraine. However, Kyiv and several Western nations have said that this is a baseless pretext for a war of choice by Putin.

During Wednesday’s address, Putin said the decision to involve citizens who have served in the Army before was taken to protect the sovereignty and territorial integrity of Russia.

“If the territorial integrity of our country is threatened, to defend Russia and our people, we will use all means we have,” Putin said, according to the BBC. “This is not a bluff.”

He added: “Those who try to blackmail us with nuclear weapons should know that the prevailing winds can turn in their direction.”