How long will the US be able to launch rockets into space with Russian engines

The head of Roscosmos, Dmitry Rogozin, said that as a result of retaliatory sanctions from Russia, the United States

There are only 4 RD-181 rocket engines left. Discuss

Rogozin noted that this number of units is enough for two launches of Cygnus cargo ships to the ISS, which are transported by Antares rockets.

“As a result of our retaliatory sanctions, the United States has only four RD-181 engines left. They are enough for two Cygnus launches, ”Rogozin wrote in his Telegram channel.