Operation Ivy was a Californian ska punk band that formed in Berkeley, California, and was often credited with spurring the 1990s punk revival in California. It is well known as one of the first bands to "mix" hardcore punk with elements of ska, known as ska-core. The band consisted of Jesse Michaels (lead vocals), Tim Armstrong (credited as "Lint") (guitar, vocals), Matt Freeman (credited as "Matt McCall") (bass, vocals), and Dave Mello (drums). Although Operation Ivy had little mainstream success during its career, the band had a large underground following and influenced bands such as Sublime and Green Day. Its only studio album, Energy, has been cited as one of the greatest punk rock albums of all time. The band's name, previously used by the punk band, Isocracy, was derived from the Operation Ivy series of nuclear tests.

The band existed between May 1987 and May 1989, as was chronicled in the lyrics of the Rancid song "Journey to the End of the East Bay", which was featured on ...And Out Come the Wolves (1995) (from the song "Spirit of '87")

Operation Ivy was the eighth series of American nuclear tests, coming after Tumbler-Snapper and before Upshot-Knothole. Its purpose was to help upgrade the U.S. arsenal of nuclear weapons in response to the Soviet nuclear weapons program. The two explosions were staged in late 1952 at Enewetak Atoll in the Pacific Proving Ground in the Marshall Islands.

The first Ivy shot, Mike, was the first successful full-scale test of a multi-megaton thermonuclear weapon ("hydrogen bomb") using the Teller-Ulam design. Unlike later thermonuclear weapons, Mike used deuterium as its fusion fuel, maintained as a liquid by an expensive and cumbersome cryogenic system. It was detonated on Elugelab Island yielding 10.4 megatons, almost 500 times the bomb dropped on Nagasaki. 8 megatons of the yield was from fast fission of the uranium tamper, creating massive amounts of radioactive fallout. The detonation left an underwater crater 6,240 ft (1.9 km) wide and 164 ft (50 m) deep where Elugelab Island had been. Following this successful test, the Mike design was weaponized as either the EC-16 or TX-16, but it was quickly abandoned for solid-fueled designs after the success of the Castle Bravo shot.

Jesse Michaels (born April 2, 1969) is a songwriter, vocalist, guitarist and artist from Berkeley, California. He is the son of the deceased author Leonard Michaels. His lyrics deal with politics, racism, and general social issues.

In February 1987, he published his first fanzine, Kill Deal for 50 Cents. Later that year he formed Operation Ivy with guitarist Tim Armstrong, bassist Matt Freeman, and drummer Dave Mello. They quickly became a popular band especially at the Berkeley punk club 924 Gilman Street. In 1988, the group released its debut extended play Hectic on which Michaels wrote all of the songs. It was followed with an American tour which brought the group's work all around the country, and made Operation Ivy a very well respected band. Operation Ivy recorded and released its only studio album Energy in 1989 and broke-up the same year. Michaels later formed Big Rig in 1994. Big Rig released one extended play and played several gigs around 924 Gilman Street before breaking up. In 1999 after a long hiatus he formed Common Rider with Squirtgun bassist and renowned producer Mass Giorgini. They released two albums and toured around the country before breaking up in 2003. In August 2008, Jesse went on a short Southern California tour with long-time friend Jeff Ott, playing new solo songs. In December 2008, he participated in a small Northern California tour with Mike Park and Kevin Seconds, as well as formed a new band, Classics of Love.