It would be "unacceptable" for Ukraine to "simply give up territory" in any peace deal with Russia, the head of the Ukrainian armed forces has told Sky News.
General Oleksandr Syrskyi said a "just peace" can only be achieved if fighting is halted along current frontlines and then for negotiations to take place.
Signalling a complete lack of trust in claims by the Kremlin that it wants to end its war, he accused Vladimir Putin of using an attempt by Donald Trump to broker peace talks as "cover" while Russian troops try to capture more land by force on the battlefield.
Ukraine peace talks - latest
The rare intervention offers the clearest indication yet of the Ukrainian military's red lines as Washington tries to negotiate a settlement that - according to an initial draft - would require Kyiv to surrender the whole of the Donbas region in the east of the country to Moscow.
President Volodymyr Zelenskyy, backed by the UK and other European allies, has been trying on the diplomatic front to strengthen Ukraine's position.
But President Putin has said Russia would either seize the Donbas militarily or Ukrainian troops would have to withdraw.
Europe's fate at stake
Speaking frankly, General Syrskyi, commander-in-chief of the armed forces of Ukraine, signalled that his country's soldiers would fight on if diplomacy fails - and he warned that the fate of the whole of Europe is at stake.
In an exclusive interview in the basement of a building in eastern Ukraine - the location of which we are not disclosing for security reasons - he said Ukraine's main mission "is to defend our land, our country, and our population".
"Naturally, for us it is unacceptable to simply give up territory. What does it even mean - to hand over our land? This is precisely why we are fighting; so we do not give up our territory."
Many troops have died fighting for Ukraine since Russia first seized the peninsula of Crimea and attacked the regions of Donetsk and Luhansk, which comprise the Donbas, in 2014.
Hundreds of thousands of Ukrainian civilians were then mobilised to fight alongside professional soldiers following Putin's full-scale invasion in February 2022.
Russia well short of original goal
Nearly four years on, Russia occupies almost a fifth of Ukraine, including large parts of the Donbas, but well short of an original goal of imposing a pro-Kremlin government in Kyiv.
Asked whether the sacrifice of those people who gave their lives defending their country would be in vain if Ukraine is forced to hand over the land it still controls in the Donbas to Moscow, General Syrskyi, speaking in Ukrainian through a translator, said: "You know, I do not even allow myself to consider such a scenario.
"All wars eventually end, and of course we hope ours will end as well. And when it does, a just peace must be established.
"In my understanding, a just peace is peace without preconditions, without giving up territory. It means stopping along the current line of contact."
The commander then broke into English to say that this means: "Stop. A ceasefire. And after that negotiations, without any conditions."
Switching back into Ukrainian, he said: "Any other format would be an unjust peace, and for us it is unacceptable."
Ukraine's contingency plans
While Ukraine's will and ability to fight are key in confronting Russia's much larger army, so too is the supply of weapons, ammunition and other assistance from Kyiv's allies, most significantly the US.
But, with the White House under Donald Trump, becoming less predictable, the Ukrainian military appears to be considering contingency plans in case US aid stops.
Asked whether Ukraine would be able to continue fighting if President Trump did halt support, General Syrskyi said: "We are very grateful to our American partners and all our allies who have been supporting us throughout this war with weapons and equipment.
"We hope they will continue providing full support. But we also hope that our European partners and allies, if necessary, will be ready to provide everything required for our just war against the aggressor.
"Because right now we are defending not only ourselves, but all of Europe. And it is crucial for all Europeans that we continue doing so, because if we are not here, others will be forced to fight in Europe."
General's assessment of fighting on ground
A decorated commander, with the call sign "snow leopard", General Syrskyi has been conducting combat operations against Russia's invasion for more than a decade.
He was made military chief in February 2024 after President Volodymyr Zelenskyy sacked the previous top commander. General Valerii Zaluzhnyi is now Kyiv's ambassador to London.
General Syrskyi offered his assessment of the fight on the ground, saying:
• Ukrainian troops still control the northern part of the fortress city of Pokrovsk in the Donbas and will keep battling to retake the rest of it, contrary to Russian claims to have captured what has been a key target for Moscow for the past 16 months.
• Russia is firing between 4,000 to 5,000 one-way attack drones at Ukrainian positions along the frontline every day as well as 1,500 to 2,000 drones that drop bombs. But Ukraine is firing the same volume - and even more - back. "In terms of drones, there is roughly parity. At the moment, we are deploying slightly more FPV [first person view] drones than the Russians."
• Russia's armed forces still have double the volume of artillery rounds of Ukraine's, but the range and lethality of drone warfare mean it is harder to use artillery effectively. Now, 60% of strikes are carried out by drones.
• More than 710,000 Russian soldiers are deployed along a frontline that stretches some 780 miles (1,255km), with the Russian side losing around 1,000 to 1,100 soldiers a day, killed or wounded "and a majority are killed".
The Russian army is currently "attempting to advance along virtually the entire frontline," General Syrskyi said.
Where are the harshest battles?
The fiercest battles are around Pokrovsk, as well as the northeastern city of Kupiansk, in Kharkiv region, the Lyman area, also in the Donbas, and near a small city called Huliaipole, in the Zaporizhzhia region of southeastern Ukraine.
"The Ukrainian army is conducting a strategic defensive operation, aiming to contain the enemy's advance, prevent them from breaking deeper, inflict maximum losses, and carry out counter-offensive actions in those sectors where we see the enemy is vulnerable," the commander said.
"Our strategy is to exhaust the Russian army as much as possible, prevent its advance, hold our territory, while simultaneously striking the enemy in the near rear, the operational depth, and… into Russia itself, with the aim of undermining its defence capability and industrial capacity."
He is referring to a capability Ukraine has developed to launch long-range drones, laden with explosives, deep into Russia to strike military targets as well as oil refineries.
The operation is aimed at destroying fuel for the tanks, warships and jets that are attacking Ukraine and - crucially - reducing oil revenues that help to fund Russia's war machine.
Sea drones crash into Russia's warships
The Ukrainian military is also deploying explosive sea drones that are smashed into Russian warships as well as tankers used to transport sanctioned Russian oil.
Asked if his forces were ready - and had sufficient manpower - to keep fighting if necessary, General Syrskyi said: "We have the resources to continue conducting military operations."
Yet Ukraine is suffering from a shortage of troops on the frontline.
Soldiers and wider society are also exhausted and facing another winter of war.
No sign of Moscow winding down war effort
President Putin has an advantage when it comes to troop numbers and firepower over time, which makes continued support to Kyiv from its allies more vital than ever.
General Syrskyi cautioned that Moscow showed no sign of winding down its war effort despite the Russian leader telling President Trump he is prepared to negotiate.
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"So we do everything so that if the enemy continues the war, and you can see that although we want peace, a fair peace, the enemy continues its offensive, using these peace talks as cover," he said.
"There are no pauses, no delays in their operations. They keep pushing their troops forward to seize as much of our territory as possible under the cover of negotiations."
He added: "So we are just forced to wage this war… protecting our people, our cities and towns, and our land."
The commander said this is what motivates his soldiers.
"If we do not do this, we can see clearly what the Russian army leaves behind, only ruins, only deaths."
As for whether the UK and other European nations should be preparing their people for the possibility of a wider war with Russia, the general said: "Of course, the armed forces of every country ensure reliable protection of their citizens, their children, and their territory.
"With the existence of aggressive states, above all the Russian Federation and its allies, this issue is extremely urgent.
"Everything must be done to ensure the capability to maintain a level of defence, and armed forces modern enough to repel aggression, both individually and in support of the allies."
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