Military build-up around Ukraine [Infographic]
Russia is upping the ante in Ukraine with an eye on the 25th anniversary of Ukraine’s independence on August 24 and the G20 summit on September 4.
Russia has positioned thousands of troops to the north in Bryansk, to the east near Rostov, to the south in Crimea and to the west in the separatist Moldovan region of Transnistria.
Ukrainian intelligence agencies say a Russian air defence regiment has been embedded with the separatists in Donbass.
Moscow annexed Crimea from Ukraine in March 2014 after a hastily called referendum, and a conflict between Russian-backed separatists and Ukrainian forces flared up in eastern Ukraine weeks later.
As soon as Russia forced the last Ukrainian troops based in Crimea to leave in 2014, Moscow set up fortified border crossings and sent new weapons to the peninsula - from cutting-edge fighter jets to the newest missile systems.
Despite the military build-up, hardly any disturbances or let alone cross-border shootings have been reported in Crimea since the annexation.
The 2015 peace agreement for eastern Ukraine signed in Minsk has helped reduce fighting in eastern Ukraine, but peaceful settlement has floundered.
The deal obliged Ukraine to grant broad autonomy to the rebel regions before it can fully regain control of the border with Russia, but those provisions have not been implemented.
Independent Moscow-based military analyst Pavel Felgenhauer said that if the Kremlin wanted to make gains or solidify its positions in Ukraine, now would be a good moment because the world's attention is elsewhere.
"The temptation is high to try and use this occasion to solve the Ukrainian problem once and for all," he said.
"While America is right now not very operational because it's in a midst of a divisive election campaign, Europe is also divided - on Brexit, on refugees, on sanctions against Russia."
Moscow refused to recognise Ukraine's interim authorities after Ukraine's pro-Moscow president, Viktor Yanukovych, was driven from power by protests, but later recognised Petro Poroshenko.