Russia has deployed over a dozen fighter jets to Ukraine amid rising tensions between the countries.

In November, Russia fired on and seized three Ukrainian ships after it says they entered Russian waters.

Ukraine has called for international military support and banned Russian men of military age from entering the country.

More than a dozen SU-27 and SU-30 fighter jets which Russia is deploying to boost its air force, amid heightened tensions with Ukraine, arrived in Crimea on Saturday.

A Reuters witness saw the jets land at Belbek air base in Crimea, which was annexed by Russia in 2014 after Moscow-leaning Ukrainian President Viktor Yanukovich fled Kiev following street clashes and violent protests.

Read more: Russia confirms it fired at Ukrainian ships in major escalation of Crimea tensions

Tensions between Moscow and Kiev have risen in the past weeks after Russia seized three Ukrainian navy ships and their crews on Nov. 25 in an incident which Moscow and Kiev have blamed on each other.

Russia fired on, and seized, three Ukranian vessels after it says they entered Russian waters. Ukraine says that Russia had been given notice about the ships who allegedly needed to cross through Russian waters.

Since the incident tensions have quickly escalated. Ukraine has asked Germany to increase its presence in the Black Sea to deter further action from Russia. Ukraine has also barred Russian males of military age from entering the country, fearing that Russia will build its forces against the country by sending unmarked soldiers across the border.

Russian Foreign Minister Sergei Lavrov has alleged Ukraine was preparing "a provocation" near Crimea before the end of the year.

(Reporting by Vladimir Soldatkin; Editing by Alexander Smith)