Russian and Chinese naval combat vessels were en route to the Aegean Sea Friday where they planned to conduct joint military exercises from Sunday through Thursday, according to a report. The combined training will be the latest in a series of Russian land, sea and air military drills conducted throughout the world in recent months.

Called the “Joint Sea 2015 Drills,” the exercises will involve nine vessels, including two Chinese frigate-class warships and a Russian guided missile carrier from the Kremlin’s Black Sea Fleet, Russian-owned outlet Tass reported.

“A group of combat ships comprising the Linyi and Weifang frigates from the Chinese navy and the Samum missile hovercraft from the Russian Black Sea Fleet have today completed passing through the Bosphorus and Dardanelles straits area and entered the Aegean Sea,” a Russian navy spokesman said.

The drills in the Aegean Sea will occur weeks after Russia’s Northern Fleet conducted anti-submarine training exercises. Those drills reportedly included Russia’s first-ever use of underwater drones and unmanned vehicles in a military capacity. Russian President Vladimir Putin previously ordered the Northern Fleet to undergo a “snap combat readiness drill” in March, CNN reported.

Western leaders, including those in the European Union and the NATO military alliance, have expressed concern over the last year amid a marked increase in Russian military activity, particularly in Eastern Europe. The European Union imposed economic sanctions against Russia last year as punishment for its annexation of Crimea last March and purported involvement in the conflict in Eastern Ukraine, which has killed more than 6,000 people since it began last year.

NATO has also taken steps to increase its military preparedness, including the implementation of an expanded rapid reaction force capable of deployment within 48 hours. Despite increased military and political tension, NATO Secretary-General Jens Stoltenberg earlier this week downplayed the notion that the military alliance was involved in a new Cold War with Russia.

“But neither are we in the strategic partnership that we tried to develop between NATO and Russia,” Stoltenberg said. “We are in something which is different, therefore we have to adapt our lines to a new security environment, and that’s exactly what we are doing.”