Had WW2 begun when Hitler invaded Poland? Britain was not yet involved. Did WW2 only begin after Pearl Harbour? It can be argued China and Japan begun their respective roles in WW2 in 1937 with Japans brutal invasion of China upon the Nanjing massacre. https://en.wikipedia.org/wiki/Nanjing_Massacre My argument is that at the very least least for Russia, Ukraine and Israel and multiple combatant groups aligned against Israel in the Middle East, WW3 has begun...and they are all only able to engage in such conflict on such a scale because they are backed by either China or the USA.

When I meant WW3, I kind of meant an all out war. Not small skirmishes.