Ukrainians told to shelter from possible Russian missile attack on Kyiv as U.S. and NATO wrestle with how to help

With the U.S. and NATO wrestling over how to help Ukraine defend itself from Russia's brutal aerial assault without becoming ensnared in a potentially much wider war, residents of Ukraine's capital got messages Wednesday warning them to take shelter "immediately" due to the apparent threat of a new wave of Russian airstrikes.

With Russian forces massed around Kyiv "failing to make any significant breakthroughs," according to the latest British intelligence assessment, Putin has relied on his military's overwhelming firepower to batter Ukrainian cities from afar. Ukraine says Russia's indiscriminate artillery barrage has killed thousands of civilians, left entire cities cut off from food, water and electricity and sent more than 2 million people fleeing into neighboring countries in a refugee crisis that grows by the hour.