The first of around 260 Russian trucks carrying aid have crossed into a rebel-held area of eastern Ukraine, with the move slammed by the Ukrainian government as a "direct invasion".
A Russian spokesman said that the Kremlin would no longer tolerate further obstructions on the trucks heading for Luhansk, following concerns from some factions that the vehicles could be concealing military personnel.
At least 90 trucks have crossed over the border, Reuters reports, filled with water, medicines, generators and sleeping bags for civilians caught up in the violence.
It is understood that their advance into Ukraine had been initiated without permission from the government and without a previously-agreed Red Cross escort - instead accompanied by a handful of pro-Russia fighters.
The Red Cross tweeted this morning: "The #Russian #AidConvoy is moving into #Ukraine, but we are not escorting it due to the volatile security situation.
"We've not received sufficient security guarantees from the fighting parties. Our team in #Lugansk reports heavy shelling overnight. #Ukraine."
Ukraine has said that while it did not give formal approval for that amount of trucks to pass, it allowed them to so as to avoid "provocations", the Foreign Minister said. It had previously officially cleared just a few dozen.
Ukraine's Security Service head Valentyn Nalyvaichenko said the invasion "happened for the first time under the cover of the Red Cross".
The convoy continued despite both sides in the conflict ignoring pleas for a ceasefire. Ukraine confirmed it would not launch air strikes against the convoy.
"Ukraine will liaise with the International Committee of the Red Cross so that we, Ukraine, are not involved in provocations that we have been holding up or using force against the vehicles of so-called aid," a spokesperson said.
Ukraine crisis: Russian 'aid' convoy
Ukraine crisis: Russian 'aid' convoy
1/11 Ukraine crisis
Drivers of the first trucks of the Russian aid convoy parked in the city of Luhansk on 22 August
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An employee inspects the contents of a truck with Russian humanitarian aid in Mariupol, Ukraine on 22 August 2014
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The convoy nearing the border before it parked at a camp in Russia
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Russian convoy carrying humanitarian aid for residents in rebel eastern Ukrainian regions moving along a road in the city of Voronezh, about 530 km from Moscow, Russia
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An Ukrainian border guard checks passing cars at a checkpoint of Pletnyovka, Kharkiv region on Ukraine-Russia border, where Russian humanitarian convoy is to cross the border
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Ukrainian border guards stand at the Ukrainian-Russian border crossing
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Trucks of a Russian convoy carrying humanitarian aid for Ukraine are parked at the military air base outside Voronezh
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Drivers of a Russian convoy of trucks carrying humanitarian aid for Ukraine take a rest on a side of a road near the city of Yelets
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An Ukrainian soldier stands guard at a checkpoint of Pletnyovka, Kharkiv region on Ukraine-Russia border, where Russian humanitarian convoy is to cross the border
10/11 Ukraine crisis
A Russian convoy carrying humanitarian aid for residents in rebel eastern Ukrainian regions moves along a road about 50 km from Voronezh, Russia, 14 August 2014. The convoy continues to advance through Russian territory after a one-day stop in Voronezh in full coordination with and under the aegis of the Red Cross, according to Russian authorities
11/11 Ukraine crisis
The Russian convoy carrying humanitarian aid in the Voronezh region of Russia en route to Ukraine
The Ukrainian city of Luhansk is plagued by fighting between separatists and government forces and has experienced continued shelling for weeks.
A statement on the Russian foreign ministry's website said that its side “has decided to act”.
“Our column with humanitarian aid is starting to move in the direction of Luhansk.”
The trucks sent from Russia had been stalled within a no-man’s land near the border for over a week.
It was thought that international Red Cross workers and border guards had inspected some of the fleet as it waited, but that much of the rest haven't been, according to Ukraine's Security Council.
Russia had promised that the convoy was no Trojan Horse and expressed frustration at Ukraine for its “endless, concocted delays” and for its shelling of residential areas that the convoy would need to pass through.
A Russian customs spokesman, Rayan Farukshin, told the Associated Press yesterday: “There is increasingly a sense that the Ukrainian leaders are deliberately dragging out the delivery of the humanitarian load until there is a situation in which there will no longer be anyone left to help.”