Ukraine has begun testing surface-to air missiles over the Black Sea, in a move which has escalated tensions with Russia.
Russia had criticised the tests, and threatened to shoot down the missiles if they enter airspace in the Crimean peninsula, which Russia annexed from Ukraine in 2014.
The Kremlin has ordered air defences to be placed on high alert, and launched naval defence exercises in the Black Sea off the Crimean coast.
On Thursday (1 December), Ukraine said the missiles would not enter Crimean airspace, sidestepping a potential confrontation with Russia.
Volodymyr Kryzhanovsky, a Ukrainian military official, told Ukraine's 112 TV Channel the exercises were taking place in accordance with international law in the Kherson region, at least 18 miles (30km) from Crimea's airspace.
On Monday, Ukraine warned aircraft to avoid an area of territory in the north of the Black Sea ahead of the missile tests on Thursday and Friday.
Russia's defence ministry had said the area "violates the territorial sea borders of the Russian Federation", in a note delivered to the defence attache at the Ukrainian embassy, according to Interfax news agency.
It warned that missiles detected in the areas would be shot down and launchers destroyed.
On Thursday, Russia's federal aviation agency, Rosaviatsia, said it had received new coordinates for the tests that meant the "danger zone reserved for missile launches does not now affect the airspace over Russian territorial waters".
Russia and Ukraine have been at loggerheads since the 2014 Maidan protests, which ousted pro-Moscow President Viktor Yanukovych from power. The annexation of Crimea provoked the worst tensions between Russia and the West since the end of the Cold War, with the EU and U*S denouncing as illegal a referendum in which voted to join Russia.
The election of Donald Trump as US president has concern in Ukraine that Washington could renege on its support, after he expressed his desire for closer US ties with Russia.