Sri Lanka, July 31 -- The ISIS terrorist organization is threatening to launch new attacks in San Francisco, New York, and London, according to new warning messages posted on the group's social media channels.

The messages, carried across the internet via the Telegram networking website, feature the three cities and call for adherents of the terror group's radical ideology to "kill them all," according to copies of the warnings obtained by the Middle East Media Research Institute, or MEMRI, a group that monitors jihadi networks.

"The pro-Islamic State Ash-Shaff Media Foundation shared five posters on Telegram which threaten and encourage terror attacks in the West.

"The posters are captioned in poor English and feature background image...