Is the United States said to be following a policy of isolation when it joins a world organization such as the?

Is the United States said to be following a policy of isolation when it joins a world organization such as the United Nations?Is the United States said to be following a policy of isolation when it joins a world organization such as the?
On paper it isn't being isolationist, but in the case of the UN, for example, the US can participate as much or as little as it wants to (hence staying isolationist). The US resists almost every potential agreement with the UN because it doesn't like the idea of answering to any authority but itself. This is a very isolationist attitude.