Russia staged military drills in the Black Sea, south of Ukraine, on Wednesday and said it needed to sharpen the combat-readiness of its conventional and nuclear forces because of heightened Nato activity near its borders.
Ukraine, which with its ally the US has said it believes Russia may be preparing an invasion, staged exercises of its own near the border with Belarus.
The increase of military activity on both sides follows weeks of rising tension that have raised the risk of war between the two neighbours, even though Russia denies aggressive intent and western intelligence sources have told Reuters they do not see any invasion as imminent.
The US and Nato have signalled their backing for Ukraine in ways that Moscow considers provocative, including through warship manoeuvres this month in the Black Sea and a delivery of US patrol boats to the Ukrainian navy.
Russian fighter planes and ships practiced repelling air attacks on naval bases and responding with air strikes during military drills on Wednesday in the Black Sea, Interfax reported.
Separately, the news agency quoted defence minister Sergei Shoigu as saying the need for Russia to further develop its armed forces was dictated by “the complicated military and political conditions in the world and the growing activity of Nato countries near Russia’s borders”.
He said raising the armed forces’ capabilities, supporting the combat readiness of nuclear forces and strengthening the potential of non-nuclear deterrence were among the priorities.