"Kindly explain that comment in light of the fact that the US has recently invaded two of them and routinely places "sanctions" on many more."

For example, we don't decide that country X, shouldn't have nuclear weapons and then tell the country X they can't have nuclear weapons.

Another example, we don't decide that country Y shouldn't allow women who are 12 year old to get married and tell country Y that it can't allow women who are underaged to get married.

In other words we do not dictate our demands on another country- we do not rule other countries, we do not pass laws for other countries.

We do enforce laws that other countries have agreed to follow. For example, if a country wants nuclear technology and they make an agreement that if given nuclear technology, they wouldn't persue making nuclear weapons. Then they can not legally make nuclear or buy nuclear weapons. They have made an agreement and it's in American's interest to do all that it can to ensure that international agreement are followed. Without enforcement of international agreement, international agreement can't have any meaning and we can not live in a peaceful world.