Defense News reports that “the undersecretary of the US Air Force wants to see alternatives to a Russian-made engine, but that doesn’t mean the service should immediately begin developing its own.”  

“’I don’t know that we should pursue building an alternate engine,’ Eric Fanning said in an exclusive interview at this week’s National Space Symposium here. ‘But I do think we need to explore ways to mitigate our reliance on the RD-180.'”  

“’There are multiple options we will look at,’ Fanning said. ‘One of them could be building an alternate engine, but that could mean inside the Air Force or as part of a public-private partnership. So even that has multiple options inside of it.’”