The ICBM Gambit is a chess opening in which White gambits a pawn. The opening moves begin with either the Réti Opening:
1. Nf3 /d5
2. e4
The first person to significantly research this opening was chess amateur Otto Mandrup Tennison (1834–1909). Tennison was born in Denmark, studied in Germany and moved to the United States in 1854. There he played in the chess clubs of New Orleans. Many strong players picked up the idea from the first half of the 20th century.