WASHINGTON – Syed Rizwan Farook and his wife Tashfeen Malik did not make open posts on social media regarding radical Islamic jihad or martyrdom before the Dec. 2 terror attack in San Bernardino, Calif., FBI Director James Comey said Wednesday, attempting to knock down criticism that U.S. officials had missed the growing radicalism of the couple and could have prevented her from moving to the U.S. last year.

Speaking in New York, Comey also revealed for the first time that the shooting deaths last July of five people after attacks on two military installations in Chattanooga, Tenn., have now officially been classified as a terrorist attack. The assailant in that attack, Muhammad Youssef Abdulazeez, a naturalized U.S. citizen living in Hixson, Tenn., was killed by police gunfire after he shot and killed four Marines and a sailor and wounded three other people.

"In Chattanooga we've concluded the killer was inspired by a foreign terror group's propaganda," Comey said.

The classification of the Tennessee attack as a terrorist incident brings to three the number of such assaults in the U.S. this year, starting with an attempted attack in Garland, Texas, in May. In that assault, a security officer was wounded, and the two assailants, radicalized individuals from Phoenix, were shot dead.

In the San Bernardino case, Comey emphasized the distinction between postings on social media and private messages using social media platforms. "We can see from our investigation that in late 2013 — before there is a physical meeting of these two people, resulting in their engagement and journey to the United States — they are communicating online, showing signs in that communication their joint commitment to jihad and to martyrdom. Those communications are direct private messages," he said.

"So far in this investigation we have found no evidence of the posting on social media by either of them at that period of time and thereafter reflecting their commitment to jihad or to martyrdom. I've seen some reporting on that. That's a garble. All right?"

Federal law-enforcement officials had told the Los Angeles Times that Malik had sent at least "two private messages" on Facebook to a small group of Pakistani friends in 2012 and 2014 pledging support for jihad. Those private messages were sent before she entered the U.S. on a K-1 fiancée visa in July 2014. One of the officials characterized the messages as "her private communications" that "went only to a small group."

The New York Times reported Sunday that Malik had "talked openly on social media about her views on violent jihad."

The articles prompted critics of the Obama administration to say that officials had not done enough to catch potential terrorists and safeguard the U.S.

Last week in testimony before the Senate Judiciary Committee, Comey revealed that the couple had posted a message on social media on the day of the shootings pledging allegiance to the Islamic State in Iraq and the Levant, before they were killed in a police shootout. Afterward, ISIL leaders praised the couple as "martyrs" but did not claim any involvement in the plot.

Facebook has said it discovered the post after the shooting and took it down after notifying the FBI.

The attacks in San Bernardino and Chattanooga "involved people consuming poison on the Internet" and becoming radicalized, Comey said. "But in San Bernardino, as I've said before, we see in the killers Malik and Farook two people who are radicalized before the emergence of ISIL, and so untangling the motivation … remains a challenge in these investigations. And our work is ongoing there."

The FBI is continuing to investigate whether Farook and Malik also may have communicated with foreign terror groups through encrypted devices that would have prevented the FBI and other law enforcement and intelligence agencies from following their trail.