Russia’s defense ministry plans to sign a contract for a preproduction batch of fifth-generation Su-57 fighter jets, Russian Deputy Defense Minister Yuri Borisov said on Thursday. This reported by TASS.

"We are buying Su-57 jets for test combat use. First stage state trials are over," he told journalists. "This year, we will sign a contract for the first batch of 12 Su-57 fighter jets for the Armed Forces."

According to Borisov, the first two planes of this batch may come into service in 2019. He said that ten out of 12 previously manufactured jets are undergoing flight tests.

When asked about performance of the new engine for Su-57, he answered: "So far, it is difficult to say because there have had been only one flight. Everything seems to be all right. But you know, it is a series of trials. Many flights are to be performed. As a rule, such trials take two or three years," he said.