Russia announced yesterday that it has delivered three more RD-180 engines to ULA for use in its Atlas 5 rocket.
The article notes that this contract, as well as the contract with Northrop Grumman to make RD-181 engines for the Antares rocket, both end in December 2019. While ULA has said it plans to replace the Russia engine with Blue Origin’s BE-4 engine (still under development), it is not clear what Northrop Grumman will do.
In both cases, Russia has delivered enough engines to cover launches for the next few years. This will give Blue Origin time to complete development of the BE-4. As for Antares, the lack of its Russian engine, combined with its inability to obtain any customers other than NASA, could spell the end of that rocket once Northrop Grumman has used up its engine stockpile.