This story was update July 17 to note that Energomash removed its annual report from its website after a Russian news outlet alleged Energomash copied its risk analysis from a space industry blog.

MOSCOW — Russia’s premier rocket engine manufacturer, Energomash, has raised the alarm on the looming cut-off of U.S. purchases of RD-180 and RD-181 engines: the end of the company’s most lucrative revenue stream is coming, Energomash wrote in its annual report last week, and it is coming far sooner than anyone anticipated.

In a section of the report dedicated to risk analysis, Energomash notes the 2018 U.S. National Defense Authorization Act limits purchases of Russian rocket engines after December 31, 2022. “However, taking into account the timing of production of launch vehicles, Russian enterprises will begin experiencing negative consequences as early as 2020,” the report says.

After the publication of this story, a Russian news outlet alleged Energomash copied a portion of its risk analysis from a Russian-language space industry blog. Energomash has since deleted the annual report from its website. They have not yet responded to a request for comment from SpaceNews.

United Launch Alliance relies on the RD-180 to power the Atlas 5 rocket it mostly uses for U.S. government launches. Northrop Grumman Innovation Systems, meanwhile, uses the RD-181 to power Antares rockets that launch Cygnus cargo tugs to the International Space Station for NASA. ULA and Northrop Grumman buy the engines from RD Amross, a Florida-based joint venture of Energomash and Pratt & Whitney.

Energomash is by far the most dependent Russian space industry enterprise on American money. According to its annual report, over half of its revenue is provided by foreign contracts, with the rest coming from the Russian state. In production terms, their dependence is far greater: of 19 engines it has on order for 2018, 17 of them are for U.S. customers.

Senior Russian space officials, such as the new Roscosmos chief Dmitry Rogozin, have often shied from admitting that U.S. efforts to wean off of their dependence of Russian space technology will be a problem. Energomash has not. Already, in January, Energomash chief Igor Arbuzov said the company is hoping for an increase in domestic orders.

But Energomash is facing a potentially daunting gap. There is no domestic demand for Energomash’s premier products — the RD-180 and RD-181 engines. There is only demand for the RD-171, of which two will be produced in 2018 for the new Angara rockets. But Angara is not yet in serial production and it is unclear when those production lines will be launched.

Further complicating this question is the fact that Angara’s fate is intimately tied to that of the Proton rocket. Both are produced by the Khrunichev space center, which was recently tasked by Rogozin to wrap-up production of Proton in Moscow, and move on to serial production of Angara after relocating its production floor to Omsk.

There are many factors that can delay this process on both ends, with optimistic estimates in the Russian press floating 2021 as a possible window for making this switch. If serial production of Angara is delayed, there is only one other conceivable domestic customer — Energia, which last year was awarded with contracts to develop a new rocket known as the Soyuz-5.

Soyuz-5 is reported to use, at least at this stage in the design process, a modernized RD-171 engine. Again, with optimistic estimates, test flights of this rocket have been slated for 2021. But few space industry firms in the world ever meet such targets.

It is likely that Energomash will find itself in a lurch during the early 2020s and the Russian state will have to foot the bill.