LONDON — The British Army said on Wednesday that it was investigating a video showing soldiers using an image of Jeremy Corbyn, the opposition Labour Party leader, for target practice.

The cellphone footage was first posted on Snapchat, according to the British broadcaster Sky News. It later migrated to Twitter, and shows four soldiers lining up with guns and firing paint rounds at a larger-than-life portrait of Mr. Corbyn, according to Sky News and the BBC.

A caption on the video reads, “Happy with that.”

It was unclear when the video was made, but according to the BBC, the soldiers were from the Third Battalion, the Parachute Regiment, known as 3 Para.

Alistair Bunkall, a defense correspondent for Sky News, wrote on Twitter that the footage had been taken at a range in Kabul, Afghanistan, where soldiers carry out “guardian-angel” drills, practicing to protect top officials. Pictures of other celebrities appeared at the range, but not for target practice.