This is a poorly thought out argument, which made it a bad argument.
The world is filled with ideas. Some are parallel. Some are contestant. An example would be when the US rebelled against the British Crown. The colonists have a different idea on how they should live. The Crown disagreed. They fought. The colonists won. Then the US came to be. But was the American colonists against the Crown the only contestant ideas at that time? Hardly.
Here is a list of 18th century conflicts that were about the same time as when the colonists fought against the Crown...
Today, despite a shared terrible past, the US-UK alliance is one of the world's strongest. The two modern countries have differences but not enough to go to war over. We can say that the US-UK are parallel ideas. The point here is that the US does not 'need' any enemy or nemesis because as long as someone else have a different idea on how to live and does not like the American way, there is going to be conflict. Ideas needs the human agency to survive and propagate. Whenever we encounter a different idea, we naturally recoil. It is a protective move. If I do not protect what I have, I will be changing my mind with every new idea I meet. So I have to initially reject what I just found. Then if I chose to examine the new idea, I will do so, and if I find the new idea attractive, I will change my mind. That is how we all want the world to work.
But not everyone is patient enough to allow others to change their minds, so they resort to conflict, which naturally make me resistant to change my mind. Convince me, not force. If I am powerful enough to resist force, that is your problem, not mine. Do not blame me for taking your believers if they happened to find my idea more attractive than yours. That attraction was why East Germans jumped The Wall or Cubans risked shark infested waters to float to the US. But we do not see West Germans jumped The Wall or Americans floated to Cuba, do we?
Regarding to what is happening today. Poutine have been in power in Russia since 2000. That is 22 yrs of preserving the Russia idea. But why? In those 22 yrs, Poutine got wealthier and wealthier while the Russians got nowhere. Poutine preserved, not improved. If Poutine had improved the Russia idea, maybe Ukraine would have petitioned Russia to share in that idea. Instead, Ukraine looked westward and Poutine got mad because this beautiful Ukrainian girl looked at another man. If you do not improve your house, why should she stay? If you do not improve your body, why should she make love to you? Have you looked at all the critical social and economic statistics for Russia lately? They sucks, and anyone would say that kindly.
The US do not need to 'have an enemy'. They always find US so we have to be ready to defend the America idea. You are free to create your own idea, but do not b!tch if your citizens starts eyeballing US.