In today’s newsletter: As Rwandan-backed M23 rebels seize more territory and the humanitarian crisis worsens, what’s the background to the war and prospect of peace?

Good morning. Over the weekend, the presidents of the Democratic Republic of the Congo (DRC) and Rwanda – Félix Tshisekedi and Paul Kagame – were among those who took part in a regional summit aimed at ending the resurgent violence in eastern DRC. The summit ended with a call for an immediate and unconditional ceasefire. But while there was a lull in the fighting yesterday, many fear that a ceasefire is less likely than escalation to a wider regional war.

Rwanda does not officially admit to its involvement in the latest episode of the long-running and devastating conflict in eastern DRC. But M23, an armed group with Rwanda’s tacit and practical support, has taken the capital of North Kivu province, Goma, and is now moving south to expand the territory under its control. At stake is control of a mineral-rich region of crucial strategic significance, and the fate of civilians there who are frequently the subject of ethnically targeted attacks – but also the question of whether national borders can act as any sort of constraint.

Arms trade | Britain’s system for controlling arms exports is broken, subject to political manipulation and has seen conduct that crossed the threshold into complicity with war crimes, a former UK diplomat has claimed. Mark Smith said officials were instructed to manipulate findings on the misuse of UK arms by allies.

Immigration | The Home Office is launching a fresh wave of immigration raids as Labour attempts to counter the growing political threat from Reform UK. Amid anger from critics who believe the approach echoes Theresa May’s “hostile environment” regime, the government will broadcast footage of deportations from detention to removal centres and on to waiting planes.

Israel-Gaza war | Israeli forces have withdrawn from the strategic corridor that divides northern and southern Gaza, as part of a ceasefire plan that has brought a fragile pause to the 16-month war. Despite the withdrawal – and the release of hostages and prisoners – little progress has been made on negotiating the second phase of the deal.

Air pollution | More than 1,100 people a year in the UK are developing the most prevalent form of lung cancer as a result of air pollution, the Guardian can reveal. Health experts, cancer charities and environmental campaigners said the UK findings were “devastating”

Trump tariffs | Donald Trump has said he will announce new 25% tariffs on all steel and aluminum imports into the US on Monday that would affect “everybody’, including its largest trading partners Canada and Mexico, in another major escalation of his trade policy overhaul.