A Ukrainian general wearing camouflage and a bulletproof vest looks out from his Mi-8 helicopter flying over the Sea of Azov, the flashpoint of rising tensions between Kiev and Moscow.

‘Our presumed enemy is Russia. We don't have any other enemies,’ says Sergiy Nayev, Ukraine's commander of military operations in the pro-Russian separatist east of the country.

The 48-year-old general is observing from the skies anti-aircraft defence exercises near the village of Urzuf on the coast of this small sea, after the Russians seized three Ukrainian military ships and 24 sailors nearby on 26 November.

Ukraine's soldiers are practising repelling a Russian attempt to land on the coast. The ex-Soviet republic believes it is now under threat of a ‘total war’ from Moscow.

‘Did you see? We got it!’ shouts Nayev as a surface-to-air missile destroys a rocket representing in the exercise an enemy plane.

The incident at sea last weekend was the first open military confrontation between Kiev and Moscow since Russia's annexation of Crimea in 2014.

Kiev has imposed martial law for a month in its border regions as it claims Russia is reinforcing its military presence at the Ukrainian frontier.

Nayev says Russia has moved ‘more than 150 planes and helicopters (and) more than 250 tanks’ near the regions of Donetsk and Lugansk, which are partly controlled by the rebels.

The military exercises at Urzuf on 29 November were planned in advance and take place every two months, but this time in a more tense atmosphere.

‘Here, some 30 Russian planes could attack,’ says the general, explaining why he has beefed up the anti-aircraft defences.

As for the separatists, they ‘don't have any planes but they have tanks and artillery. All that comes from Russia,’ Nayev says - an accusation Moscow denies despite evidence to the contrary.

Two Su-25 fighter planes and two Mi-24 helicopters are taking part in the exercise along the Ukrainian coast of the Sea of Azov not far from the key port of Mariupol.

‘By sea, Russia is only about 30 miles from here,’ says Nayev.

But he says the Russians don't come to this area of the Azov. ‘One day, two ships came but I sent out two military planes and they left.’

And if the Russians did show up, the Ukrainian defence ‘is capable of destroying many Russian planes,’ says Nayev.

Nor should they try to come by sea, the general adds.

‘The enemy will not land here. It would not make any sense for him to do that since we will retaliate.’