STANFORD, Calif. (KTVU) -- U.S. authorities have heightened concern over ISIS and the possibility of a domestic terror attack during the upcoming Fourth of July holiday weekend, with one part of that concern revolves around the terror group's ability to recruit sympathizers through social media and the internet.
The question is: how extensive is their reach and what can the United States do to thwart the terror group's efforts?
A few keystrokes can be the key to opening a conversation with anyone, anywhere in the world. That's something ISIS has used to its advantage, expanding its reach through the internet and social media.
"What's known is that ISIS has a very sophisticated media strategy," said Herb Lin, a cyber security expert at the Hoover Institution and Senior Researcher at Stanford's Center for International Security and Cooperation.
Lin says U.S. officials have big challenges in the online battle.
ISIS and supporters are able to post propaganda videos, such as a series titled "mujatweets", showing Islamic State personnel passing out candy to children. The video was distributed on YouTube and other sites. The group has also posted more grisly images of hostages beheaded and global calls for new recruits.
"ISIS doesn't have lawyers. They don't have different departments that have to coordinate. They can operate more quickly in this space than we can and this is a problem that we don't yet know how to solve," Lin said.
A Brookings Institute study published in March tried to get a handle on on the number of Twitter accounts by ISIS sympathizers. Researchers found an estimated 46,000 ISIS-linked accounts between September and December of 2014. Twitter suspended about 1,000 of those.
"There's nobody in the U.S. government who thinks we are doing this perfectly," Lin said.
A bill was introduced in Congress last week to create a homeland security program to fight ISIS propaganda online.
Stanford University senior researcher Martha Crenshaw, an expert on terrorism, says terror groups are increasingly trying to recruit lone attackers.
"They find lonely people who are looking for some cause, for guidance, for superior wisdom, for something to believe in. And they groom them, in effect, and we have studies of how this has happened," said Crenshaw.
Experts say the United States can develop more strategies for better monitoring, faster response to online threats, and more partnerships with social media companies.
"Their skills are not greater than everybody else skills by any means. They have just exploited this opportunity that's out there," Crenshaw said.
It's unclear whether the U.S. will form a special unit to battle ISIS online, but this month European Police (EUROPOL) did form a unit. Their goal is to shut down any site within two hours.