There is a fear that if the war becomes a protracted stalemate then western interest will be hard to maintain, ITV News Europe Editor James Mates and Producer Jenny Klochko report.
After weeks of heavy fighting in the eastern city of Sievierodonetsk, Ukraine will begin withdrawing its troops to more defendable positions, the Governor of Luhansk announced on Friday.
Russia has controlled around 95% of the Luhansk region for more than a month now, but Ukraine's army has defended the key city of Sievierodonetsk and neighbouring Lysychansk fiercely.
The city now lies in all but ruins, with heavy shelling destroying most infrastructure, and footage from soldiers on the frontline giving an insight into just how close the street fighting has become.
The capture of Sievierodonetsk has been a key strategic goal for Russia throughout this war.
Alongside the capture of Lysychansk - which lies across the river and for now remains under Ukrainian control - it would allow them to take the entire Luhansk area, which, with Donetsk makes up the Donbas region.
On Friday, in an interview with ITV News, Ukraine’s Military Intelligence Chief, Kyrylo Budanov, told us the retreat was both "tactical" and "organised", and that he still believes it's possible for Ukraine to win the war by the end of the year.
"In order to achieve a strategic victory, our command decided to regroup on new positions. And I personally believe this decision to be correct," he said.
"The defence of Ukraine has been going on for four months, and the defence of Sievierodonetsk has been going on for a little bit over four weeks. Our forces there will not be destroyed, this will not happen."
"This is only a tactical regroup. And, as you can see, a tactical regroup is going on in Ukraine as a whole. In certain areas of the frontline we are successfully counterattacking, in certain areas of the frontline we are successfully defending," added Budanov.
Despite recent Ukrainian setbacks in the east - caused by Russia's heavy offensive after re-focusing its efforts away from elsewhere in Ukraine to Donbas - Budanov emphasizes that the Ukrainians are making gains elsewhere, most notably on the Southern front, in Russian-occupied Kherson.
"You will have seen that in the Mykolaiv and Kherson direction there is a certain change. It's only a matter of time for Kherson," he says.
"Ukraine will return to its borders of 1991, there will be no other scenarios and we are not considering any other scenarios. Beginning in August, certain events will take place, that will demonstrate to the whole world that the turning point begins to take place."
"I have said it before and I'll say it again - before the end of the year, active fighting will decrease virtually to nothing. We are adamant in our view. We will regain control over our territories in the foreseeable future," he added.
He acknowledges that much of the Ukrainian army's success in this war now hinges on international support, noting the UK's recent offer of military training for 10,000 Ukrainian troops.
"The UK's help in the training process is significant - they are giving us high-precision equipment, which requires training. Without it we wouldn't be able to operate it efficiently. This is an excellent example of co-operation and help."
"But we always have a lack of arms - we need more arms," he adds.
Budanov remains steadfast in his army's ability to push back russia's invasion: "putin will not succeed. This is a tragedy that he led russia and Ukraine to, and it will end up as a catastrophe for Russia. Nothing else."