By August 2014, the Ukrainian "Anti-Terrorist Operation" was able to vastly shrink the territory under the control of the pro-Russian forces, and came close to regaining control of the Russo-Ukrainian border. Igor Girkin urged Russian military intervention, and said that the combat inexperience of his irregular forces, along with recruitment difficulties amongst the local population in Donetsk Oblast had caused the setbacks. He addressed Russian president Vladimir Putin, saying that: "Losing this war on the territory that President Vladimir Putin personally named New Russia would threaten the Kremlin's power and, personally, the power of the president". In response to the deteriorating situation in the Donbas, Russia abandoned its hybrid approach, and began a conventional invasion of the region. The first sign of this invasion was the 25 August 2014 capture of a group of Russian paratroopers on active service in Ukrainian territory by the Ukrainian security service (SBU). The SBU released photographs of them, and their names. On the following day, the Russian Defence Ministry said these soldiers had crossed the border "by accident". According to Nikolai Mitrokhin's estimates, by mid-August 2014 during the Battle of Ilovaisk, there were between 20,000 and 25,000 troops fighting in the Donbas on the separatist side, and only between 40% and 45% were "locals".