Using Russian engines, like the ISS collaboration was an attempt by the US to keep soviet rocket scientists in business in civilian roles so they wouldn't be incentivized to spread around the world proliferating ICBM tech.

In the process the US paid a huge price (decay of domestic design capability) and it's debatable if the goal was achieved.

Edit: Thankfully the decay has been made up for over recent years with the boom in private launch companies and of course, SpaceX's work.