In the north a 50,000-strong Russian force is attacking Sumy, a provincial capital. Our model is detecting artillery fire and explosions along the city’s northern defensive lines. Ukraine is badly outnumbered but officials say the front is holding.

Kyiv was the main target of an hourslong assault that killed at least two people, officials said. The barrage came hours before the top American and Russian diplomats met.

Russia’s attacks on Ukraine are escalating, both on the front lines and across urban centres. Ben Hall, the FT’s Europe editor, talks to military analyst Franz-Stefan Gady about Ukraine’s battle to hold onto territory until a ceasefire can be agreed.