The Islamic State released a video on Tuesday purporting to show the beheading of American hostage Steven Sotloff, raising the stakes in its confrontation with Washington over U.S. air strikes on its insurgents in Iraq.

Photographs purportedly showing more than 40 UN peacekeepers seized by Islamist militants on Syria’s side of the Golan Heights – along with their identity cards – have been posted on social media.  The al-Qaeda linked Nusra Front says the captives, all from Fiji, were detained on Thursday because their UN mission was helping Syria’s government and had ignored the suffering of its people. It says they are being treated well.

The extremists who have seized large parts ofSyria and Iraq have riveted the world’s attention with their military prowess and unrestrained brutality. But Western intelligence services are also worried about their extraordinary command of seemingly less lethal weapons: state-of-the-art videos, ground images shot from drones and multilingual Twitter messages.

This may be the best Ice Bucket Challenge to combine the viral video craze with what’s in the news right now.  Militants of the Islamic State of Iraq and Syria have been mocked by one social media user who has imitated what an ISIS member would look like if he were to accept the challenge.

The proliferation of social media has brought extremist ideologues world-wide into closer and more personal contact with potential recruits than antiterror officials ever dreamed possible, but it also has handed Western investigators powerful new tools for tracking potential threats.

In the past week or so, major social media events have included a funeral, a police shooting, and a beheading. I don't mean to suggest that the ceremony for Mike Brown in Ferguson, the shooting of Kajieme Powell a few miles away, or the Islamic State's beheading of James Foley in Syria were primarily social media events. They are all tragedies, which have taken and shattered lives.

As Scotland's September referendum on independence approaches, groups both for and against separation from the United Kingdom are making efforts to appeal to undecided voters. But one particular advertisement has caused a fury of commotion online.  Scottish Twitter users had mostly negative initial reactions to the advertisement, which was widely considered condescending and outdated.

Hollywood celebrities aren’t the only ones whose tweets go viral these days. Some military leaders are taking to social media just as other government leaders and agencies are.  The Central Intelligence Agency, for example, made headlines in June with its first tweet: “We can neither confirm nor deny that this is our first tweet.” It was shared more than 50,000 times in its first hour.