According to the Ukrainian defence ministry, two Ukrainian armoured artillery boats and a tugboat were fired at, rammed, and then seized by Russian forces. Russian Navy Spetsnaz boarded the damaged vessels and captured their crews. Firsthand reports stated that at least two Ukrainian sailors have been wounded in action. The two armoured artillery are the Berdyansk and the Nikopol, the tugboat is the Yani Kapu.

According to a Ukrainian Navy spokesperson, the three vessels were intending to cross into the Sea of Azov through the Kerch Strait, a narrow water lane situated between Crimea and the Russian mainland.  The vessels began their journey from the Black Sea port of Odessa and were heading to the Ukrainian port of Mariupol. Since tensions erupted in 2014, Russia has been monitoring the Kerch Strait closely, at times even shutting it off. The Russian Navy is currently using a tanker to completely shut off the Strait.

Moreover, Russian Air Force Su-25 fighter jets and Kn-52 helicopters are patrolling the area. The Su-25 is often used in a Close Air Support role. Additionally, both aircraft can carry anti-ship missiles — reportedly even the Kh-35 missile, a subsonic projectile that could easily sink a small ship (for example, a frigate) or seriously damage a large one (for instance, an aircraft carrier).

The Russian Ministry of Defence cited security reasons for blocking the Strait. Regarding the ramming and boarding of the Ukrainian vessels, the Ruusians stated that it happened because they were trying “to create a conflict situation in this region [after] illegally entering a temporarily closed area of Russian territorial waters.”

The Ukrainian government, however, rejected these accusations and emphasized that it had informed its Russian counterpart about the vessels’ scheduled trip. Earlier this month, Ukrainian vessels had performed the exact same journey and were even escorted by Russian tugs under the bridge that covers the Kerch Strait. Ukrainian President Petro Poroshenko has called an emergency war cabinet. He called Russia’s actions a breach of the United Nations (U.N.) Convention on the Law of the Sea. The Ukrainian Ministry of Defence placed Ukrainian forces in Eastern Ukraine on high alert and the rest of the armed forces on full combat readiness.

Since 2003, and the signing of the treaty on the Sea of Azov, the shallow sea is considered internal waters for both Ukraine and Russia. Both countries have guaranteed free navigation. The event comes in the wake of a rash of accusations between the two countries over the sovereignty of the Kerch Strait.