Is Trump losing patience with Putin? Will sanctions against Russian oil giants hurt Putin? Russian forces have spread rapidly through Pokrovsk, the city in Ukraine's east where the warring sides have concentrated their manpower and tactical ingenuity during the past week, in what may be a final culmination of a 21-month battle. Geolocated footage placed Russian troops in central, northern and northeastern Pokrovsk, said the Institute for the Study of War (ISW), a Washington-based think tank. It set its sights on the city almost two years ago, after capturing Avdiivka, 39km (24 miles) to the east.

Fox News Flash top headlines are here. Check out what's clicking on Foxnews.com. Ukraine told critics of the pace of its three-month-old counteroffensive to "shut up" on Thursday, the sharpest signal yet of Kyiv's frustration at leaks from Western officials that say its forces are advancing too slowly. Nearly three months since launching a much vaunted counteroffensive using hundreds of billions of dollars of Western military equipment, Ukraine has recaptured more than a dozen villages but has yet to penetrate Russia's main defences. Stories in the New York Times, Washington Post and other news organisations last week quoted U.S. and other Western officials as suggesting the offensive was falling short of expectations.