A U.S.-based space company is expected to confirm plans to buy five previously banned Russian rocket engines by late September, the Kommersant business daily reported Wednesday, citing unidentified sources close to the Russian engine manufacturer.

A United Launch Alliance (ULA) delegation will visit the rocket engine manufacturer in Russia before the end of the month “to prove they are serious about their intent” to buy five RD-180 engines, the newspaper reported.

ULA reportedly has been engaged in secret talks for over a year with Russia’s Energomash on the purchase of 10 RD-180s. Initial plans to sign a contract in September 2016 were scrapped because of the U.S. presidential campaign and SpaceX CEO Elon Musk’s new engine tests, according to Kommersant.

Another attempt to sign the contract in France this year failed after the United States tightened sanctions against Russia.

Following Russia’s annexation of the Crimea in 2014, U.S. lawmakers banned the use of Russian engines for U.S. military and spy satellite launches after 2019. The ban has been partly lifted given the U.S. space industry’s reliance on the RD-180 engines.

Despite plans to have a reliable domestic replacement ready by 2020, ULA plans to continue launching rockets using the Russian-built engines at least through “the mid-2020s,” the Wall Street Journal quoted its spokeswoman as saying this week.

ULA has provided the majority of U.S. Air Force satellite launches since it was established in 2006 as a joint venture of Lockheed Martin Corp and Boeing Co.

Russia is expected over the course of 2017 and 2018 to supply the United States with 22 RD-180 engines under previously signed contracts.