Marines from the United States and Ukraine carried out a coordinated amphibious assault drill during exercise Sea Breeze in the Ukrainian town of Mykolaivka, the US European Command (EUCOM) said in a release on Wednesday.

The drills, which began on July 10 and will last until July 23, are taking place in the north-western part of the Black Sea in Ukraine’s Odessa and Mykolaiv regions, bringing together representatives of 17 states, including France, Turkey, the United Kingdom, the United States, and involving 31 ships, 29 aircraft and over 3,000 troops.

“US and Ukrainian Marines launched coordinated amphibious assault from a Turkish ship against a beachhead, today, during Exercise Sea Breeze in Mykolaivka, Ukraine,” the release stated.

The European Command said the coordinated action showed a high-level of military interoperability among US and its partners.

The Sea Breeze war games are annual multinational drills that train maritime, air defense, anti-submarine, and search and rescue operations, with the aim to strengthen cooperation among NATO allies in the Black Sea region.

In January, the Ukrainian parliament adopted a law allowing foreign troops to be present in the country in 2017 to participate in multinational drills. The document outlines the admission of the US military, military of other NATO member states and the countries participating in the NATO’s Partnership for Peace program totaling up to 3,000 personnel with weapons and military equipment, up to six aircraft and helicopters for up to 365 days in January-December 2017.