Rides into space and rocket engines are not the only thing USA needs Russian Federation for [0] and [1]. (The second reference has a misleading url; the artcile's actual title is "Why the U.S. Is Buying Natural Gas From Russia").
The US has superior launch capability to Russia. SpaceX performed more launches all by itself in 2017 than all of the large Russian nation that has been doing space launches for 60 years. That gap is about to get dramatically worse over the next five years.
[0] https://www.rt.com/business/415345-united-states-buying-russ...
[1] https://www.bloomberg.com/news/articles/2018-01-19/how-the-u...