[Give it up. Nobody wants WWIII over Ukraine. Besides it is election time and pine boxes make angry voters.]
This stuff about fearing escalation in the event of more extensive supply efforts is BS. Russia supplied North Korea and North Vietnam with its best stuff - jet fighters and anti-aircraft hardware in a war against a nuclear power. Did the US nuke Moscow? That would be a no. Going slow on supplying Ukraine while bloviating about freedom is basically Moscow Joe’s way of paying Putin back for the bribes funneled through Burisma without risking impeachment, given the bipartisan consensus in favor of arming Ukraine.