When the US intelligence community first picked up signs in the fall that Russia could be preparing a new attack on Ukraine, President Joe Biden directed his administration to act -- and fast. Wary of repeating mistakes made in 2014, when the US and Europe were caught off guard by Russia's annexation of Crimea, Biden directed his national security team to use every tool possible to try to deter Russian President Vladimir Putin while a possible invasion was still assessed to be several months away, a senior US official told CNN.
"What we have been doing is very calculated," the official said. "But we only have about a four-week window from now" to pull it off, he added. The response began with a flurry of intense diplomatic activity in early fall, including a trip by CIA Director Bill Burns to Moscow to warn Putin directly against making a move. But as Russian troops continued to amass near Ukraine's border, the quiet diplomacy quickly evolved into stark, public warnings to Putin to back down or face harsh sanctions and increased US military assistance to Ukraine. Top Biden officials are now emphasizing that the consequences would go above and beyond anything Russia faced after its land grab in 2014.