Ukraine and Russia: What you need to know right now

* Russia's state news agency TASS said many Ukrainian fighters had surrendered in Metolkine, quoting a source working for Russian-backed separatists. * Ukraine's defence intelligence directorate said on Saturday five Ukrainian civilians had been returned in a swap for five Russian prisoners.

The war in Ukraine could last for years, the head of NATO said, calling for steadfast support from Ukraine's allies as Russian forces battle for territory in the country's east. FIGHTING * The eastern industrial city of Sievierodonetsk, a prime target in Moscow's offensive to seize full control of Luhansk - one of the two provinces making up the Donbas - faced heavy artillery and rocket fire again, the Ukrainian military said. * Ukraine's military said "the enemy has partial success in the village of Metolkine," just southeast of Sievierodonetsk. * Russia's state news agency TASS said many Ukrainian fighters had surrendered in Metolkine, quoting a source working for Russian-backed separatists. * Britain's defense ministry said there had been little change in the front line on the axes to the north, east, and south of the Sievierodonetsk pocket. * Analysts at the Washington-based Institute for the Study of War think tank wrote that "Russian forces will likely be able to seize Sievierodonetsk in the coming weeks but at the cost of concentrating most of their available forces in this small area". * Russian forces trying to approach Kharkiv, which lies northwest of Luhansk and is Ukraine's second-largest city, aimed to turn it into a "frontline city", a Ukrainian interior ministry official said * A fuel storage depot in Novomoskovsk, northeast of Dnipro, exploded, killing one person and injuring two after it had been hit by three Russian missiles, the regional administration chief said in an online message.. * Reuters could not independently verify battlefield reports.

DIPLOMACY * British Prime Minister Boris Johnson warned of a need to prepare for a long war, which meant ensuring "Ukraine receives weapons, equipment, ammunition, and training more rapidly than the invader". PRISONERS * Two top commanders of fighters who defended the Azovstal steel plant in the southeastern port of Mariupol have been transferred to Russia for investigation, Russia's state news agency TASS reported. * Ukraine's defense intelligence directorate said on Saturday five Ukrainian civilians had been returned in a swap for five Russian prisoners. It did not say whether the Russians were combatants.