Moscow unilaterally closes the international waterway to start construction. Only Russian ships can now sail through it. The closure is a serious blow to Ukraine’s fragile economy. The cities of Mariupol and Berdiansk, along the northern shore of the Sea of Azov, are the largest exporters of Ukrainian steel to the West. Russia’s action contravenes a treaty signed by Russia and Ukraine in 2003. In 2014 Russia annexed Crimea.

The Ministry of Infrastructure of Ukraine plans to file a complaint with the International Maritime Organisation over Russia’s decision to close unilaterally Kerch Strait, an international waterway. This follows Moscow’s decision in June to close the strait to build a bridge to Russian-occupied Crimea.

The Ukrainian government is reportedly compiling data to estimate the economic damage to the country likely to result from Russia’s announced closure of the strait for 23 days in August and September.

Kerch Strait is the gateway connecting the Black Sea to the Sea of Azov. The strategically important Ukrainian port cities of Mariupol and Berdiansk, along the northern shore of the Sea of Azov, are two of the biggest exporters of Ukrainian steel to the West. Thus, closing the strait for any length of time would have a debilitating effect on the fragile Ukrainian economy.

In its announcement Moscow said that no maritime traffic will be allowed, except for Russian vessels for yesterday, between 6 am and 6 pm.

Construction of the 20-kilometre long Kerch Strait Bridge is estimated to cost around US billion. The road section of the bridge is slated for completion in December 2018, with the rail link scheduled for the following year.

Russia’s action contravenes a treaty signed between the two countries. In October 2003, hostilities nearly erupted between Ukraine and Russia in an incident known as the Tuzla Straits Crisis, when Russia started to build a dam from the Taman peninsula to Tuzla Island.

The international crisis led to the agreement signed on 24 December 2003 on the use of the Sea of Azov and the Kerch Strait. In it, Russia and Ukraine agree to co-operate in the use of the sea and the strait.

The document determines that the Sea of Azov is an internal waterway for both countries. It further states that merchant vessels and other state non-commercial vessels flying the flags of the Russian Federation and Ukraine have free navigation in the Sea of Azov and the Kerch Strait.

Crimea, a Ukrainian region with a Russian-speaking majority, was annexed by Russia after a controversial referendum on 16 March 2014 in which a majority of residents indicated their desire to come under Russian sovereignty.

About 81.3 per cent of eligible voters are said to have voted with 96.77 per cent opting for annexation to Russia. Earlier, some 20,000 Russian soldiers without insignia had seized the peninsula.

Reacting to the poll, the Ukrainian constitutional court declared the referendum illegal. Russia’s annexation has not been recognised internationally.

With the construction of the bridge, Russia is showing its clear intention of ensuring the union between the region and the “fatherland”.