Ukraine’s missile tests in the Black Sea have reportedly prompted Russian forces to go on “high alert.” Kiev proceeded with the tests despite Russian threats to shoot the missiles down.

“It is our responsibility to build air defense for Kyiv and the whole of Ukraine and no one can stop us,” declared President Petro Poroshenko on Thursday, as quoted by Radio Free Europe.

A military spokesman offered assurances the exercises would occur at least 30 kilometers from Crimean airspace, and the tests would be held in accordance with international law. Ominously, he added that the Ukrainian military was prepared for “any developments.”

Russia responded by bringing its warships off the coast of Crimea to a “higher state of alert,” according to a military source in Crimea. The Russian Foreign Ministry denounced the missile test as a “new large-scale provocation” intended to “escalate the conflict between Ukraine and Russia.”

UPI quotes the Russian Defense Ministry claiming that the Ukrainian tests would “violate the territorial sea borders of the Russian Federation.”

Russia’s civil aviation authority, Rosaviatsiya, complained that Ukraine made a “unilateral decision to conduct missile launches in Russia’s sovereign airspace” but said it would cancel all flights through the area Ukraine designated as dangerous during the test period.

Ukraine shifted the test area somewhat to address Russia’s concerns, but the Russian Foreign Ministry still complained the missile tests would set a “dangerous precedent.”

“I want to emphasize that the launches are taking place in open sea over Ukrainian airspace, in full accordance with international law. The launches will go on regardless of any statement released by Moscow. The only reason that makes us conduct these exercises is the need to be consistently ready for any full-scale invasion from the side of our aggressive neighbor,” Poroshenko responded.

On Thursday, a spokesman for Poroshenko said 16 Ukrainian S-300 medium-range missiles were tested successfully. No response from Russian air defenses was reported.