Soldiers from Russia's Western Military District have started large-scale air defence exercises at Kapustin Yar testing range in Astrakhan Region, amid increasing tensions with the West over Ukraine.
Involving 3,500 troops and more than 1,000 units of military and special hardware, the month-long drills are scheduled to culminate with live-firing drills, involving S-300, Buk-M1 and other mobile air defence systems, RIA Novosti reports.
Western Military District spokesman colonel Oleg Kochetkov said the exercise will bring all of the district's air defence units, including coastal defences of the Northern Fleet in one place for the first time.
"It is the largest-ever exercise held by air defence units of the Western Military District," Kochetkov said, adding that the drills form part of Russia's regular combat training cycle.
The drills coincide with the unveiling of a co-ordinated set of sanctions, such as visa restrictions on Russians travelling to Europe, by the US and European Union (EU) allies in response to Moscow's occupation of Black Sea peninsula of Crimea, an autonomous Ukrainian region with a majority ethnic Russian populace.
Meanwhile, the Crimean regional government refused to recognise Ukraine's new central government as legitimate, and announced a decision to become part of Russia, following a vote in the Parliament.
Crimean vice-premier Rustam Temirgaliev was quoted by The Guardian as saying: "From today, as Crimea is part of the Russian Federation, the only legal forces here are troops of the Russian Federation, and any troops of the third country will be considered to be armed groups with all the associated consequences."
A referendum to approve the decision is scheduled to be held in Crimea on 16 March.
Denouncing the referendum, acting Ukrainian Prime Minister Arseniy Yatseniuk said: "Crimea was, is and will be an integral part of Ukraine.
"In case of further escalation and military intervention into Ukraininan territory by foreign forces, the Ukrainian Government and military will act in accordance with the constitution and laws."