Ukraine has accused Russia of launching a "direct invasion" by sending an aid convoy of military trucks across the border without its permission, in a move that ramped up east-west tension ahead of today's visit to Kiev by German chancellor Angela Merkel.
After waiting near the border for more than a week, the convoy of almost 300 trucks started crossing into Ukraine after Russia said it would not wait any longer for clearance from a Kiev government whose legitimacy it disputes.
Moscow insists it only wants to help people in eastern Ukraine who have endured months of fighting between pro-Russian rebels and government forces.
Kiev suspects the trucks will be used to halt its troops’ military advance against the insurgents and could give Russia a pretext to invade if the convoy comes under real or staged attack.
Western states and organisations lambasted Russia's decision to send the trucks, but Kremlin leader Vladimir Putin justified the move in a telephone conversation with Dr Merkel ahead of her Kiev visit.
“We consider this a direct invasion,” said Valentin Nalivaychenko, the head of Ukraine’s security service.
The Red Cross had said it was willing to distribute the aid in eastern Ukraine under certain conditions, but said yesterday it would have nothing to do with the convoy after failing to receive proper security guarantees.
Only about 35 trucks had been inspected by Ukrainian customs staff when the convoy crossed the border, and Kiev’s foreign ministry said: “Neither the Ukrainian side nor the International Committee of the Red Cross knows the content of the trucks. This arouses special concern.”
Ukrainian president Petro Poroshenko, who is due to meet Dr Merkel today and Mr Putin in Minsk on Tuesday, said it was a "flagrant violation of international law" to send in the convoy without his country's permission.
“We are doing everything in our power for this not to result in more serious consequences,” he added.
Mr Nalivaychenko insisted Ukraine’s forces, which have made major gains against the Russian-backed rebels in recent weeks, would not use force to stop the convoy.
“Russia must remove its vehicles and its personnel from the territory of Ukraine immediately. Failure to do so will result in additional costs and isolation,” said Pentagon spokesman John Kirby.
Sebastien Brabant, spokesman for EU foreign policy chief Catherine Ashton, said: "This is a clear violation of the Ukrainian border . . . We urge Russia to reverse its decision."
Nato secretary-general Anders Fogh Rasmussen warned that the "blatant breach of Russia's international commitments . . . can only deepen the crisis in the region, which Russia itself has created and has continued to fuel."
He said the developments were “even more worrying as they coincide with a major escalation in Russian military involvement in eastern Ukraine since mid-August, including the use of Russian forces.”
The Kremlin said Mr Putin had told Dr Merkel that in light of “obvious procrastination” from Ukraine, Russia had decided to send in the convoy because “further delay would have been unacceptable.”