Zond 4, part of the Soviet Zond program and an uncrewed version of Soyuz 7K-L1 crewed Moon-flyby spacecraft, was one of the first Soviet experiments towards crewed circumlunar spaceflight.

It was launched to test the spaceworthiness of the new capsule and to gather data about flights in circumterrestrial space.

[1] The spacecraft was successfully launched by a Proton D-1e on 2 March 1968 into a 400,000 km apogee orbit 180 degrees away from the Moon.

[2] It was launched away from the Moon probably to avoid trajectory complications with lunar gravity.

A ballistic re-entry would mean no recovery on Soviet soil, so the APO destruct system automatically blew up the capsule at 10 to 15 km altitude, 180–200 km off the African coast at Guinea.