A Chabad rabbi told me that after the State of Israel happened, people stopped opposing it since its existence must have been from Hashem. So then they started supporting it.
Context: I had just read a book (I think it was by Chaim Potok) that talked about the tensions between Misnagdim and Chassidim. The book also mentioned the resistance against the State of Israel. That was news to me.
So I asked my rabbi if it was true that some people were against it.
He said yes before it was a state but after it happened then clearly Hashem had a reason and it was important to support it.
At another time, I told my rabbi that a family member told me that sometimes he regrets something he did many years ago. My rabbi said that was nothing to regret. If it happened then it needed to happen and the family member wasn’t in control. The point here is that my rabbi puts his trust in Hashem that what happens is meant to happen and we must deal with what is here, even when it differs from our will.
I am not certain that the reason Chabad now is pro-Zionist has to do with becoming more “modern.” Maybe it is part of the Baal Shem Tov’s teachings to be happy and serve Hashem with joy. Plus the Talmud’s teaching to be happy with one’s lot.