NEW YORK (CBSNewYork) — International investigators have been trying to use social media to prevent three missing London schoolgirls from joining ISIS in Syria, as President Barack Obama says it is crucial to shut down the propaganda machine that is attracting recruits.

As CBS2 Political Reporter Marcia Kramer reported, many have said it is impossible to underestimate the success of the sophisticated and slickly produced propaganda that Islamic State militants have used to attract people from all over the world to join their war machine and commit barbaric atrocities.

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“They’re self-sustained. They have plenty of finances. If you look at their website, the video campaign that they have online is very sophisticated; very well-funded,” said local terror expert Manny Gomez. “They’re able to recruit at least 50 members to their organization a day.”

Gomez said ISIS recruits from the United States and all over the world, which is why President Obama has asked world leaders to help shut down the ISIS propaganda machine.

The propaganda machine produces as many as 90,000 posts on Twitter, YouTube, Facebook and other social media platforms every single day.

“The high-quality videos, the online magazines, the use of social media, terrorist Twitter accounts — it’s all designed to target today’s young people online,” President Obama said.

Obama’s campaign came as British police were asking for help in locating the three British schoolgirls they fear left London.

The Metropolitan Police said the three girls, Shamima Begum, 15, Kadiza Sultana, 16, and a third 15-year-old who was not named at the request of her family, left their homes Tuesday morning, giving excuses to their families, met up and traveled to Gatwick Airport, south of London, together, CBS News reported.

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Two of the girls were reported missing after they failed to return home to their families Tuesday evening. The third was reported missing Wednesday morning. The girls boarded a Turkish Airlines flight and landed in Turkey on Tuesday evening, according to the Met.

London detectives said the girls could be headed to war-torn Syria to join Islamic State fighters.

“They traveled without the knowledge of their families, and we’ve had full cooperation from all three families, who are very worried about these three girls,” said Met Counterterrorism Cmdr. Richard Walton.

He said ISIS’ self-styled “caliphate,” which spans northern Syria and Iraq, “is an extremely dangerous place and we have seen reports of what life is like for them (young women) and how restricted their lives become.”

Authorities said a number of young British women who have traveled to Syria have even gone on to become “jihadi brides” to ISIS fighters.

But going after the ISIS propaganda sites poses a conundrum. Terror analyst J.M. Berger said that up to 80 percent of ISIS supporters on Twitter could be shut down, but he warned that doing so could be a double-edged sword.

“These accounts provide a lot of information about what’s going on in ISIS territories, and the question is, can you dig into this network and degrade its performance while still maintaining those benefits?” Berger said. “And I think the answer is that you can.”

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There is also a campaign in Washington to pressure sites such as Twitter to do more to censor terror-linked content. But there is no useful definition of what even constitutes terror, and releasing encrypted user information can raise major privacy issues.