Two years ago in Madrid, I watched Jeremy Corbyn launch a pan-European campaign to end arms supplies to Ukraine. As he did so, a friend in the Ukrainian army sent me a photo of the machine gun that he’d been issued with: it was made in 1944. If the west had not poured billions of pounds worth of arms and ammunition into Ukraine, its people would have been massacred and enslaved. So forgive me if I describe Mr Corbyn’s call for “peace” as a meaningless abstraction (Our leaders seem determined to give war a chance. Their thirst for conflict endangers us all, 23 April). The only peace Vladimir Putin is offering the Ukrainian people is that of the grave and, by campaigning to deprive them of weapons, Mr Corbyn is not helping. I share his dismay at the failure of western leaders to hold Israel in check, and to hold its army to account for breaches of the laws of war. But the picture he paints, of a western political class convinced that “war is the only option”, is false. De-escalation – in Ukraine, in Gaza, in the Red Sea and with Iran – has been the watchword in western diplomacy since 2022. It has failed because, try as we might to separate these conflicts and de-escalate them, an axis of anti-western totalitarian powers is determined to do the opposite. When Mr Corbyn blames the west for “paving a path to escalation” by bombing Yemen, he ignores the fact that the Houthi rebels began the escalation by firing on civilian ships, and that our own Royal Navy is acting entirely within international law by defending them, and the working-class seafarers aboard them. The world’s descent into warfare and inter-ethnic violence is truly terrifying. But when faced with aggression, either from Putin, the Houthis, Hamas, Hezbollah or Iran, abstractions are not enough. The Labour tradition I share with Mr Corbyn is founded on an heroic switch, in 1936-37, from pacifism to anti-fascism, and from disarmament to rearmament. Then, as now, abstract calls for peace served as useful cover for those who wanted to appease dictators. Mr Corbyn should emulate his former Labour colleagues in parliament; support arms for Ukraine and support the Royal Navy as it defends civilian shipping in the Red Sea. Paul Mason Journalist, film-maker and author • Do you have a photograph you’d like to share with Guardian readers? If so, please click here to upload it. A selection will be published in our Readers’ best photographs galleries and in the print edition on Saturdays.