Syria purchased 36 Yakovlev Yak-130 Mitten fighter planes from Russia for $550 million, the Russian daily Kommersant reported Monday.
The deal, signed in December, specifies that production of the planes will begin once initial payments are made.
In January, Russian Foreign Minister Sergei Lavrov said Russia has no intention to justify its arms sales to Syria.
"We don't consider it necessary to explain ourselves or justify ourselves, because we are not violating any international agreements or any (UN) Security Council resolutions," Lavrov told an annual news conference.
A Russian-operated ship with "a dangerous cargo" reached conflict-torn Syria in early January, a source at the vessel's St. Petersburg-based firm said, after being temporarily halted during a refueling stop in Cyprus.
In December, Russia delivered anti-ship cruise missiles to Syria, according to the Interfax news agency, days after a United Nations commission of inquiry called for an arms embargo on Damascus.
Reuters contributed to this report.