The EU’s warning comes after Russia’s president said he could use “all the means available to us”.
The EU must not ignore Vladimir Putin’s threats that he could use nuclear weapons in the conflict in Ukraine, the bloc’s foreign policy chief has said.
Josep Borrell told the BBC’s Lyse Doucet that Mr Putin’s assertion that he was not bluffing had to be taken seriously.
His remarks come as Russia begins a partial mobilisation and moves to annex four regions of Ukraine.
But Russian forces have been pushed back by a Ukrainian counter-offensive.
“Certainly it’s a dangerous moment because the Russian army has been pushed into a corner, and Putin’s reaction – threatening using nuclear arms – it’s very bad,” he said.
Seven months since Russia’s invasion of Ukraine began, analysts agree that President Putin’s forces are on the back foot, but Mr Borrell said a “diplomatic solution” must be reached, one that “preserves the sovereignty and territorial integrity of Ukraine”.
“Otherwise, we can finish the war, but we will not have peace, and we will have another war,” he said.
Ukraine has dominated this year’s UN General Assembly as this costly war drags on with no clear sense of a way out. Europe’s foreign policy chief was surprisingly blunt and visibly pained.
He shared the anxious lament he was hearing everywhere he went. From friends on holiday, to leaders from around the world attending the UN General Assembly this week, they were all asking him when this war would end. “Stop this war, I can’t pay my electricity bill,” was, he regretted, a common refrain.
Mr Borrell was willing to say in public what many express in private – that Europe and its allies were struggling to control the narrative in this war as Russia spins the view that European sanctions against Russia were to blame for this suffering.
But Moscow’s new and worrying threats, including a thinly-veiled nuclear one, are also concentrating minds. Most Western leaders, including Mr Borrell, are still categorical about the need to stay the course in a conflict with many far-reaching consequences, most of all for Ukraine, but many others too.
Mr Borrell dismissed concerns that the EU’s arms supplies were running low, and said it must continue providing military support to Ukraine, as well as applying economic sanctions against President Putin and his allies and conducting diplomatic activity.
He admitted that the rising cost of energy prices caused by the conflict was a matter of concern.
“People in my country tell me the price of the gas means we cannot continue working, we cannot continue making my business run,” the Spanish politician said, adding he had heard similar concerns from leaders from Africa, South America and Southeast Asia.
“I cannot bear the consequences of this war,” he said.
Mr Borrell called on President Putin to play his part in reaching a negotiated solution, saying “in order to dance the tango, you need two”.
“Everybody who has gone to Moscow, to the Kremlin to talk to Putin, they came back with the same answer, ‘I [Putin] have military objectives, and if I don’t get these military objectives I will continue the fight.’ This is certainly a worrisome direction, but we have to continue to support Ukraine,” he said.