Russian forces are advancing in Ukraine at the fastest rate since the early days of the 2022 invasion, taking an area half the size of London over the past month, analysts and war bloggers said on Tuesday.

Russian troops swept through swaths of Ukraine in early 2022 before being pushed back to its east and south. The 1,000 kilometer front line has been largely static for two years, until the latest, smaller-scale advances that began in July.

The war is entering what some Russian and Western officials say could be its most dangerous phase, with Russia reported to be using North Korean troops in Ukraine and Kyiv now using Western-supplied missiles to strike back inside Russia.