Ninotchka

Everything About Fiction You Never Wanted to Know.
"A Russian! I love Russians! Comrade, I've been fascinated by your five-year plan for the last fifteen years."
"The last mass trials have been a great success. There are going to be fewer but better Russians."

Ninotchka is a 1939 Metro Goldwyn Mayer Romantic Comedy, directed by legendary director Ernst Lubitsch, co-written by Billy Wilder and starring Greta Garbo and Melvyn Douglas, set in interbellum Paris and Moscow.

Three bungling Soviet diplomats aim to sell some Romanov diamonds to a Parisian jeweler to raise funds for the Soviet Union. Nina Ivanovna Yakushova, nicknamed "Ninotchka" (Garbo), an Ice Queen diplomat, is sent over to help them after they make a mess of it, where she meets and falls in love with Parisian boulevardier and aristocrat Leon d'Algout (Douglas). In this she finds herself rivaled by the diamonds' original owner, the Grand Duchess Swana (Ina Claire), who wishes to retrieve both the jewels and Leon's affections. Swana manipulates Ninotchka into abandoning Leon in order to keep the jewels for Russia. Leon, however, does not accept the situation...

The story was later remade as the musical Silk Stockings, with music by Cole Porter, which was itself adapted into a 1957 MGM film with Fred Astaire and Cyd Charisse in the Douglas and Garbo parts, respectively.

The original is in the public domain, and can be watched at the Internet Archive.

Tropes used in Ninotchka include:

Iranoff: Do you want to be alone, comrade?
Ninotchka: No.