Russia's Putin shuts the window for diplomacy

Russian President Vladimir Putin has now assembled 70% of the military personnel and weapons on Ukraine's borders he would need for a full-scale invasion of the country, according to two US officials familiar with the latest estimates.

The figure is an estimate based on the latest intelligence assessments, but officials would not specify the intelligence they had or how they developed their assessments, citing the sensitivity of how they collect the information.

The assessment represents the continuing significant buildup of Russian forces on Ukraine's borders, but it's unclear how long it would take Putin to ramp up further, or whether the Russian president would need full capabilities in order to invade.

US officials publicly and privately still say they do not know if Putin has made a final decision on any type of military action, but behind the scenes, President Joe Biden's national security and intelligence teams are calculating various scenarios and the potential outcomes.

Based on publicly available weather calculations, the optimal time for a Russian invasion would be while there is a hard ground freeze, so heavy equipment can readily move. US officials have said Putin would understand he needs to move by the end of March.

That timeline and the growing number and capability of Russian forces close to Ukraine could suggest the window for diplomacy is shutting.

Officials stress constantly the intelligence they have is leading them to make these estimates, but they are just estimates. The U.S. officials did not provide evidence to back up their estimates of Russia's forces.