It is interesting to compare the US plans as stated by Rick Perry with Europe's plans. In an interview two weeks ago with Primeur MagazineEuropean Commissioner Maria Gabriel expected that Europe, through EuroHPC, will have two pre-exascale systems ready in 2020 and an exascale supercomputer in 2023. Of course, it depends a bit on whether the US 2021 machine will turn out to be a peak-exascale system or a sustained exascale supercomputer, but the US plans seem a little bit ahead of the European ones. However, the funding for the USA second batch of exascale systems is not 100% secured yet.
Interview with Commissioner Maria Gabriel: Commissioner Mariya Gabriel sees a growing sense of community in EuroHPC exascale initiative .
US Secretary of State Rick Perry article in CNN: