When German chancellor Angela Merkel visits Kiev today, she could be forgiven for imagining she hears an ominous rumbling in the distance. Her talks with Ukraine’s leaders will begin a crucial week of negotiations aimed at ending the country’s bloody crisis, but it will now start not only with guns booming in the east, but a huge convoy of Russian military trucks rolling through disputed territory.

By sending his aid convoy into Ukraine yesterday without its permission or the co-operation of the Red Cross, Russian president Vladimir Putin sent a message of defiance to Kiev and its western allies.

He showed he is determined to regain the initiative in Ukraine, despite recent setbacks suffered by Moscow-backed rebels who want eastern regions to join Russia, and the impact of his country’s growing economic and diplomatic isolation.
The convoy of almost 300 trucks – many of which are almost empty – adds another unpredictable element to a volatile conflict that has killed more than 2,000 people and displaced hundreds of thousands. The first trucks arrived last night in Luhansk, a city that has been without power, running water and telephone connections for almost a fortnight, and an island of rebel resistance to the rapid recent advance of Ukrainian troops.

The separatist strongholds of Luhansk and Donetsk are now almost surrounded by government forces, raising hopes among Ukrainian military men that the insurgency could be crushed before tomorrow’s Independence Day celebrations.

Kiev believes the aid convoy is Moscow’s way of slowing or halting the crackdown on the rebels, and could be used to provide a pretext for a full Russian invasion if it came under attack, either real or staged.

It is not clear how long the trucks will stay in Ukraine, or even where they will attempt to go, with Russia potentially seeking to send them from Luhansk to Donetsk, through areas of fierce fighting. The convoy is Putin’s wildcard, and the fact he has played it now suggests Ukraine’s crisis is at a vital juncture.