Night vision sight PVS-2 a.k.a. 'starlight scope'
The US used 'passive' night vision devices for the first time ever during the Vietnam War.
The vision offered by the instrument was black and green.
Those very first night vision devices – huge, heavy and with a very bad definition – raised very different opinions between the soldiers. Most found them useless, while a minority of marksmen and snipers said they were essential. Since then, the US invested a lot of money to develop this technology and became the worldwide leaders in night vision warfare usage.