why? let s go outfront. good evening, i m erin burnett. outfront tonight, on the brink. president biden holding a call with key u.s. allies for roughly 80 minutes tonight over growing fears russia is on the verge of invading ukraine. the president saying everyone is on the same page. the call comes as 8500 u.s. troops are now on heightened alert to possibly deploy. as president putin shows no sign of backing down. as their presence on the border enlarged or changed in a qualitative way that ises ses escalating? yes. they are continuing to add battalion troops to their western border, to the border with ukraine. and in belarus as well. the numbers there are increasing. so they have not only shown no signs of de-escalating, but they are in fact adding more force capability. they are in fact adding more