Retaliation or Negotiation? Rogozin bans RD-180 exports to the US, while creating uncertainty about GPS and ISS

Russian Deputy Prime Minister, Dmitry Rogozin, has been reported to have ordered a ban of exports of RD-180 engines to the US, as long as the engines are used for military purposes. At the same time, he indicated that GPS stations in Russian may not be allowed after June 1, while Russia is not interested in prolonging ISS operations after 2020. However, all these developments could be seen as parts of a large geopolitical negotiation between the US and Russia.