>> How long would it take a "unified bloc" to agree on doing anything?

This is why most of the time the US does things unilaterally. Whether its militarily, economically or otherwise. We ask other countries if they want to stop China from laying huge tariffs on their products and they say, "Yes, for sure!" Then we say, "Okay, let's all impose tariffs on their imports and fight back!" and suddenly all those countries who were on board to do something suddenly get cold feet and don't want to get sucked into a trade war or deal with the short term consequences of standing up to them.

Also, these trade wars with China have been off and on since the 1970's if not earlier.