They are watching the situation closely. Our commander calls it recapitalization. Certainly, our equipment is aging, but that does not mean it is not effective for the missions assigned to us.
In addition, the Americans have a global perspective. They do not have the same considerations as we do. So when an event occurs in the world, they can decide to commit forces, when we will not do so. There are American forces engaged more or less everywhere in the world, while the scope of our work is more limited.
In the event of a series of extreme threats, there is no certainty that all their forces would be available to defend North America. That is why they are observing us closely.