Ukrainian president Petro Poroshenko said on Thursday that Russian forces had entered his country and the military situation in the eastern Donetsk region was “rapidly deteriorating.”
The aim of the Russian offensive seemed to be the Ukrainian port city of Mariupol. From there, Russia could establish an overland connection with the Black Sea peninsula of Crimea it took from Ukraine in March.
NATO released satellites images the same day which it said corroborated Poroshenko’s claim. The pictures depict Russian artillery units crossing the border and preparing for action by establishing firing positions in the area of Krasnodon, the alliance said in a statement.
Krasnodon is situated close to the Russian border and east of Luhansk, one of two major cities held by Ukrainian separatists.
An Ukrainian military commander told Ukrainska Pravda newspaper that Russian soldiers and tanks had also entered the city of Novoazovsk, east of Mariupol.
Russia continued to deny it had sent troops into Ukraine, even after eleven of its soldiers were captured in the country this week. Russia said the troops had probably crossed the border by accident.
According to Ukraine and Western powers, however, Russia has been supplying the insurrection with weapons for months, including missile launchers that were used to shoot down a commercial airliner in June, killing nearly three hundred passengers and crew.
A NATO spokesman said on Thursday that “large quantities of advanced weapons, including air defense systems, artillery, tanks and armored personnel carriers” were being transferred from Russia to the rebels in eastern Ukraine.
He added, “Russia’s ultimate aim is to alleviate pressure on separatist fighters in order to prolong this conflict indefinitely, which would result in further tragedy for the people of eastern Ukraine.”
The increase in Russian support came as Ukrainian troops had almost encircled the separatists in Donetsk and Luhansk, raising fears in Western capitals that Russia might intervene directly to prevent the uprising’s collapse.
After Poroshenko, a former businessman and proponent of closer Ukrainian ties with the rest of Europe, assumed office last month, the country’s army progressively drove back the rebels.
The speed and success of the Ukrainian offensive in the east, which is home to the country’s ethnic Russian minority, appeared to take the rebel leadership by surprise. Several Russian nationals who previously occupied key positions in the uprising resigned or disappeared.
Relations between the two former Soviet states cooled earlier this year when large street protests in Kiev forced President Viktor Yanukovich to resign after pulling out of an association agreement with the European Union in favor of closer relations with Russia. After Yanukovich fled the country, Russia occupied the Crimea which headquarters its Black Sea Fleet. It annexed the territory after a referendum found the majority of Crimeans in favor of joining the Russian Federation.
Poroshenko’s government signed the European treaty, which commits Ukraine to the gradual approximation of its economic, judicial and security policies to those of the European Union, last month.
The agreement gives Ukraine European financial support and will eventually establish a free-trade area between the country and its neighbors. It is seen as a stepping stone to European Union membership which would preclude Ukraine, the largest former Soviet republic next to Russia, from joining President Vladimir Putin’s own Eurasian Union.