Attorney General Loretta E. Lynch and FBI Director James B. Comey, shown here with President Obama, are among the national security officials flying to Silicon Valley to meet with tech executives. (Mark Wilson/Getty Images)

Much of the national security leadership of the Obama administration is flying to California to seek tech firms’ help in figuring out how to thwart terrorists who use the Internet to recruit and radicalize people and to plan attacks, according to U.S. officials.

Among those set to attend a meeting Friday with Silicon Valley top executives are Attorney General Loretta E. Lynch, FBI Director James B. Comey, Obama counterterrorism adviser Lisa Monaco, Director of National Intelligence James R. Clapper Jr., National Security Agency Director Michael Rogers and Deputy Secretary of State Anthony J. Blinken.

Companies planning to send senior executives include YouTube, Facebook, Twitter, Microsoft and LinkedIn. Apple chief executive Tim Cook is also expected to participate.

The meeting at a federal government building in San Jose, to be led by White House Chief of Staff Denis McDonough, follows President Obama’s televised call after the shootings in San Bernardino, Calif., last month for tech leaders to “make it harder for terrorists to use technology to escape from justice.”

The officials see it as a bull session to learn how they might use technology to “disrupt paths to radicalization to violence” and “identify recruitment patterns” as well as to measure efforts to countering radicalization, according to an agenda obtained by The Washington Post.

They are also interested in knowing how they can encourage others to publish content that would “undercut” the Islamic State’s message online.

The Islamic State has, like no other terrorist group before it, made effective use of the Internet to spread its message, recruit followers and inspire them to carry out attacks. Officials such as Comey have decried the group’s use of videos, social media and encrypted communications services to expand its ranks and plan attacks in the United States and Western Europe.

“As the Internet erases the distance between countries, we see growing efforts by terrorists to poison the minds of people like the Boston Marathon bombers and the San Bernardino killers,” Obama said in his address last month.

The encryption issue is also on the agenda but is not a main focus, officials said. That issue has divided the administration, with the tech and economic policy agencies supporting the use of widespread encryption and law enforcement and national security agencies concerned that such a trend is aiding terrorists and criminals. Comey’s participation in the meeting was on the condition of encryption being on the agenda, an official said.

Some of the largest social media firms have already moved to counter extremism. Facebook has been the most aggressive, adopting a zero-tolerance policy that calls for removing posts related to terrorist organizations.

That includes taking down videos of Anwar al-Awlaki, the American cleric and al-Qaeda propagandist whose sermons inspired Muslims around the world to violent jihad. Awlaki was killed in a drone strike in Yemen in 2011, but his words live on in videos that were reportedly viewed by one of the San Bernardino shooters, the Boston Marathon bombers, and the attacker in last year’s Chattanooga, Tenn., shootings.

Twitter, which has been especially outspoken about protecting freedom of speech on its platform, updated its abuse policy last year to make clear that “threatening or promoting terrorism” violated its rules.