Britain's defence ministry said on Wednesday it had launched an investigation into a video circulating on social media apparently showing soldiers using a picture of opposition Labour party leader Jeremy Corbyn for target practice.The video, posted on Snapchat, shows four paratroopers firing shots at the picture with the caption "happy with that"."We are aware of a video circulating on social media," an Army spokesperson said. "This behaviour is totally unacceptable and falls well below the high standards the Army expects. A full investigation has been launched."A Labour spokesman called the behaviour alarming and unacceptable but said the party was confident the Army would investigate and act on the incident.The soldiers have been widely criticised by lawmakers."I’m shocked obviously that this sort of thing has happened," Corbyn said. "I hope the Ministry of Defence will conduct an inquiry into it and find out what was going on and who did that."