https://www.bbc.com/news/world-europe-60506682
Air raid sirens have sounded throughout the night in major cities across Ukraine, as the Russian invasion enters its fifth day.
The Russians launched their attack on Thursday from three main directions: north, south and east.
Dozens of targets have been struck, as Russian troops have poured into Ukraine.
The fight for Kyiv
Russian forces arrived near Obolon on the outskirts of Kyiv on Friday, but so far have not advanced into the centre of the capital. The Ukrainian military says Russian troops have repeatedly tried to storm the outskirts of the capital without success.
Russian forces now control a narrow path across the Dnieper river into the east of Kyiv, according to the Institute for the Study of War.
Russian airborne and special forces troops are reported to be involved in urban clashes in northwestern Kyiv, but mechanised forces such as tanks and armoured vehicles are not yet in the capital.
On Sunday, there were reports of clashes with so-called saboteur groups on the city streets - and an oil depot was hit at Vasylkiv south of the city.
A residential block in the suburb of Bucha was hit by shelling, and there was heavy fighting in nearby Irpin.
There has also been fierce fighting at Hostomel airport, to the west of Kyiv.
Russian troops around Ukraine
Russia is now in full control of significant parts of Ukraine's territory.
After Ukraine's air defences and other military infrastructure came under attack on Thursday, columns of tanks moved into position, backed up by artillery and air power.
Troops have spread across parts of the north, east and south, with missile strikes and artillery clearing the way for advancing Russian forces.
Some analysts say overall progress by Russian troops has been slower than expected. But after the apparent pause in major operations over the weekend, the Russians could resume the offensive using greater air power and artillery support.
Strike from the north
From the north, Russian troops crossed the border into Ukraine at the three-way junction between Ukraine, Russia and Belarus, at Senkivka.
In recent weeks, a huge deployment of Russian troops gathered close to Novye Yurkovichi and Troebortno, including "the entire 41st army", according to Michael Kofman of the US-based Center for Naval Analyses.
The British Ministry of Defence says the bulk of Russia's ground forces remain more than 30km from Kyiv, their advance slowed by Ukrainian forces defending Hostomel airport.
Armoured columns, including tanks and multiple launch rocket systems, have moved towards Chernihiv, where they have faced strong Ukrainian opposition. The city faced heavy shelling from Russian troops overnight, but remains in Ukrainian hands.
A second, more rapid advance has come down the west side of the Dnieper river via Chernobyl, taking control of a large area to the north and west of Kyiv.
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Strike from the east
On Sunday morning Russian forces breached Kharkiv. There were reports of street fighting and explosions.
Images emerged showing Ukrainian troops firing rocket propelled grenades on street corners and Russian troops, on foot, moving behind armoured vehicles.
Later in the day, Ukrainian officials said the Russian attack had been repelled.