I live in south western Connecticut and there are these tree/shrubs in my area with that grow like wildfire in my area and I would like to know what it is called and what the proper techniques are to completely remove the tree. I have cut them down to the stem just a year ago and already they are huge.

These tree/shrubs grow like weeds and I suspect they are invasive... but I checked the CT invasive plants list and it was not on it.

The leaves are oval shaped with slightly pointed ends and are silver green on the bottom side. Older branches have thorn-like stubs that prick but don't pierce the skin. And I believe I have seen these shrubs grow small red berries with white dots which I think comes from tiny white flowers.