Malaysia Airlines Flight MH17 was shot down on July 17, 2014, as Ukrainian forces clashed with a separatist movement supported by Russian special forces in the eastern part of the country.
Russian President Vladimir Putin has denied responsibility for the incident, but Dutch investigators concluded that the plane was downed by a surface-to-air missile launched from separatist territory.
"Russian-led forces in eastern Ukraine fired the surface-to-air BUK missile — brought into sovereign Ukrainian territory from Russia — that took down flight MH17," State Department spokeswoman Heather Nauert said Monday.
Boris Nemtsov, a Putin critic who was assassinated in 2015, alleged in a report he was writing when he died that Russian special forces went to eastern Ukraine in the summer to blunt a Ukrainian offensive.
Russian Foreign Minister Sergey Lavrov acknowledged military involvement in Ukraine during a recent foreign policy forum alongside Henry Kissinger.