On Tuesday, as part of a huge military drill organized by Ukraine and including the United States, Poland, and Lithuania, helicopters provided air support, armored personnel vehicles rolled through fields, and soldiers fired at enemy objectives.

The drills, dubbed Three Swords-2021, will take place at Yavoriv training field in the Lviv region from July 17 to 30 and will involve over 1,200 personnel and 200 combat vehicles.

“You have seen several tactical exercises,” said Yevhen Moysyuk, commander of the Ukrainian air assault forces. “They show a high level of preparedness and the readiness of our partners to jointly repel aggression,” he told a briefing.

The drills come amid increased tensions between NATO and Moscow, which said in June it had fired warning shots and dropped bombs in the path of a British warship to chase it out of Black Sea waters off the coast of Crimea.

Relations between Kyiv and Moscow plummeted after Russia seized Crimea and over Russia’s support for separatist forces in the conflict in Ukraine’s eastern Donbass region.

Ukraine and the United States in June held a separate military exercise, Sea Breeze, involving more than 30 countries in the Black Sea and southern Ukraine, despite Russian calls for the drills to be cancelled.