The Lastochka/Finist (Russian: Ласточка/Финист, lit. 'Swallow') is a German/Russian commuter intercity electric multiple unit train used across multiple Russian cities, based on the Siemens Desiro design and manufactured by Siemens and Ural Locomotives.

In 2009, Russian Railways commissioned Siemens to develop a suburban dual-system electric train adapted to Russian conditions. The new trains were planned to be used in Sochi for suburban passenger traffic during the 2014 Winter Olympics and then to be partially transferred to other train lines with non-stop service routes.

Previously, Siemens had already produced dual-system Sapsan trains (Velaro RUS) for Russian Railways. The design of the new electric train was based on the five-car Siemens Desiro ML electric train. On 29 December 2009, Russian Railways signed a contract with the German company Siemens for the production of 54 Siemens Desiro RUS electric trains worth €410 million.

The trains received the ES1 (Russian: ЭС1 (Электропоезд Сименс мод.1), lit. 'EMU Siemens 1 model') series designation and were branded as Lastochka. All 54 trains were manufactured in Germany.

In March 2022, after Russia invaded Ukraine, Siemens put all new business and international deliveries in Russia and Belarus on hold. In June 2022 Siemens Chief Executive Officer Roland Busch condemned the war in Ukraine and announced that the company had decided to wind down its industrial business activities in Russia. In line with the requirement of Russian Railways for "technology transfer", most components for Lastochka can now be locally sourced, with over 80% of the latest trains being Russian made.

Since 2023, the Sinara Group has been implementing its own new project (based on Siemens Desiro technical solutions) - electric train ES104 under the former commercial name "Lastochka" (now "Finist").

Dual-system trains with automatic system transfer were the ideal solution for amalgamating pre-existing railway lines in the region of the Olympic Games. There, the main railway network operating in flat terrain along the coast of the Black Sea had been electrified with direct current at 3 kV, while the lines built in the mountainous section of Adler – Krasnaya Polyana had been electrified with AC voltage at 25 kV, 50 Hz, appropriate for the steep gradients, and hence much higher power demands. Dual-system electric trains allow commuter rail routes covering sections of both DC and AC track with no need to stop at places where the electric power changes. With the technology, the trains are able to run directly from Adler to Krasnodar without stopping at the Goryachiy Klyuch changeover station.

All technical solutions adopted by Siemens in the design of the new Desiro ML RUS electric trains were discussed with experts from specialized research institutes and were approved by Russian Railways. Siemens consulted many Russian experts in high-speed railways—especially those involved in the Velaro RUS high-speed trains construction—for the design decisions concerning the Desiro ML train design and construction.