(CNN)Moscow is putting on a huge show of force in Crimea, a little over two years after Russia annexed the territory.
Russia puts on show of military strength in Crimea
It is staging war games on land, air and sea in maneuvers called Kavkaz 2016, across Russia's entire southern military district on the border of Ukraine.
CNN's correspondent at the Opuk military base in Crimea, Fred Pleitgen, says the aim is clear.
"Russia is sending a very clear message with these large scale and very complex drills. Their forces are entrenched in Crimea and ready to fight at any time," he said.
"What they do in these military drills is simulate an invasion of Crimea, [and] they simulate their forces fighting off that invasion."
He says Russia's forces are more modern and better equipped than probably at any time since the end of the Cold War.
The drills involve more than 12,000 soldiers, dozens of fighter jets flying mock dog fight missions, strike aircraft hitting ground and sea targets, and land forces carrying out an amphibious assault.
But the defense ministry's spokesman insists the exercises are not a provocation.
"These maneuvers were planned well in advance," he said. "We don't want to provoke anyone. We are just testing the readiness of our forces to repel any attack in our country."
The war games come at a time of heightened tensions with the US and NATO over the annexation of Crimea and other issues.
After Crimea was seized in 2014, the US and European Union imposed sanctions on Russia which have been very painful for the country
CNN's correspondent says the Russians make very clear that they are not going to give up Crimea.
The Russian air force intercepted a US P8 naval aircraft in the region just as the drills were getting under way.
The US says the intercept was conducted in an unsafe way, but Russia denies that.
Only three weeks ago, Russia accused Ukraine of trying to smuggle operatives into Crimea for sabotage operations.
Fred Pleitgen says the Kavkaz military drills will likely cause more unease in Ukraine and the eastern European NATO member states.
Russia's military chief of staff says the initial assessment is that they went smoothly.
"We need to go and analyze everything but it seems as though the units worked together very well," he said.
Pleitgen adds that with Russia and the West at odds over Syria and Ukraine, Moscow is continuing to advance and refine its armed forces for all the world to see.