According to Russian media, 3 more military vessels from the Caspian Fleet were deployed in the Sea of Azov on May 23. These vessels are two Shmel-class river gunboats AK-201 and AK-248, one Zhuk-class patrol boat AK-326.

This passage aims at security in the Sea of Azov taking into consideration recent agressive actions in the region by the Ukrainian side.

On March 25, Ukraine illegally seized the Nord fishing vessel flying the flag of the Russian Federation in the territorial waters of Russia. On May 28, head of the FSB branch in Crimea and Sevastopol Viktor Palagin claimed that suspects of the illegal detention of the Nord vessel had been identified. According to Palagin, all the suspects, which are currently in Ukraine, were put on an international wanted list.

On April 4, a spokesperson for the State Border Guard Service of Ukraine Oleg Slobodyan said that all the ships travelling to and out of Crimea without Kiev’s consent would be detained.

On May 4, Russia’s FSB Border Department in Crimea said in a statement that the fishing vessel YMK-0041 (homeported in Ochakiv, Ukraine) had been detained for “illegal fishing” by coastguards.

On May 10, Russian coastguards reportedly detained the Ukrainian fishing boat Amur with two persons on board in the Sea of Azov.

On May 22, Russian media reported about that May 16 extramural decision of the Ukrainian seaside district court of Odessa to seize the Russian vessel Pechora for the extraction of sand on the territory of Crimea. At present, the Pechora vessel is in Crimea.

Over past months, Russian coastguards have increased pressure on the Ukrainian side in the Sea of Azov. Russian coastguards are actively carrying out searches of vessels moving to Ukrainain ports and combatting illegal fishing in the Sea of Azov.

Russian FSB Coast Guard ship fires it's AK-630 automatic multi-barrel weapon during a recent drill in the Azov Sea launched in response to the incident with the Nord

Russian forces board Ukrainian fishing vessel in Azov

Aside from the two known Ukrainian vessels detained, I have read that plenty of other Ukrainian fisherman had their catch seized, and also their equipment, like nets and such. Many now afraid to go out on the sea at all, in Azov ports in Ukraine like Berdyansk and Ochakov. In Berdyansk, there were reports of text messages passed around on cell phones within the fishing community, calling on fishermen to take to the streets against the government officials they blame for messing with the Russians and taking their ship, which caused the whole mess. Local authorities, of course, are blaming pro-Russian agitators employed by Moscow's special services, who, they say, are taking advantage of the situation and trying to stir up instability in the area.

Anyway, and now, enter these three new boats.

The Zhuk-class patrol boats are used by both Ukrainian (top) and Russian Coast Guards

The Shmel-class river gunboats are more interesting, here they are, AK-201 and AK-248

These are heavily armoured vessels (they been described as "big floating tanks"), which are relatively old (they were made in late 60s and early 70s, to patrol the Amur river, the natural boundary between Russian Siberia and China, at a time of serious tensions between PRC and USSR, and outright armed conflicts breaking out over disputed islands on the river), and fairly slow moving, especially compared to Ukraine's new Gyurza armoured cutters

But, again, their thick armour (designed, I heard, to potentially withstand Chinese shore artillery fire) will make the Gyurza's machine guns pretty much useless, in a showdown, and while the smaller Ukrainian cutter can try to run circles around the Shmel, one hit from the latter's powerful forward gun would make a mess of the Gyurza

Video shows them in a drill, on the Caspian

I believe Russia will continue moving forces into Azov. No escalation for now, with the World Cup and all. After, though, they may well move to push Ukraine out of Azov altogether...