WASHINGTON (Reuters) - Americans radicalized by online propaganda from Islamic State and other militant groups pose the main terrorist threat to the United States, which is especially vulnerable to foreign fighters returning from Syria, senior U.S. security officials said on Wednesday.






Source: [url=http://feeds.reuters.com/~r/Reuters/worldNews/~3/RbY9tlrBcDQ/story01.htm]Top U.S. security threats: lone wolves, Syria fighters : officials[/url]