Before WIENER, COSTA, and WILLETT, Circuit Judges. WIENER, Circuit Judge: The issue in this case is whether Internet services and social media providers may be held secondarily liable under the Anti-Terrorism Act (“ATA”) for aiding and abetting a foreign terrorist organization—here, Hamas—based only on acts committed by a sole individual entirely within the United States. We conclude that they cannot, and therefore affirm the judgment of the district court. * * * Plaintiff-Appellant Jesus Retana was a police officer when, in July 2016, he and thirteen other police officers were shot and either injured or killed during a tragic mass-shooting committed by Micah Johnson in Dallas, Texas. Retana survived his wounds but had to have surgery to remove a bullet from his left arm. Retana and his husband, Andrew Moss (“Plaintiffs”), sued Defendants-Appellees Twitter, Google, and Facebook (“Defendants”), all Internet services and social media providers, in federal court. Plaintiffs allege that Defendants are liable because they provided material support to Hamas, a foreign terrorist organization that used Internet services and social media platforms to radicalize Johnson to carry out the Dallas shooting. Plaintiffs claimed, inter alia, that Defendants were liable for Retana’s injuries under (1) 18 U.S.C. § 2333(a), which provides a cause of action for victims of acts of international terrorism, and (2) 18 U.S.C. § 2333(d), which extends liability to “any person who aids and abets, by knowingly providing substantial assistance” to a person who commits an act of international terrorism. The district court dismissed all claims with prejudice pursuant to Federal Rule of Civil Procedure 12(b)(6) (“Rule 12(b)(6)”). Plaintiffs have appealed only the dismissal of their ATA secondary liability claim.[1] At the Rule 12(b)(6) stage, we review the district court’s order de novo, construing the facts in Plaintiffs’ second amended complaint as true and in the light most favorable to them.[2] I. Hamas is a Specially Designated Global Terrorist organization.[3] An offshoot of the Muslim Brotherhood, Hamas is responsible for thousands of terrorist attacks in Israel, the West Bank, and Gaza, murdering Israeli citizens and citizens of other countries, including the United States. Hamas maintains accounts on Twitter, YouTube,[4] and Facebook to contact potential recruits and encourage them to commit terrorist attacks. Plaintiffs alleged that YouTube shares revenue with Hamas from advertising Hamas videos. In the summer of 2014, Johnson met with a “witness” referred to in the second amended complaint as “Ms. X.” Johnson told Ms. X that he sympathized with the Palestinian efforts—allegedly controlled by Hamas— to destroy Israel. Plaintiffs alleged that Hamas has met with “black separatist hate groups” which call for the murder of American police officers.[5] Plaintiffs alleged that Johnson was radicalized by reviewing Hamas posts and those of these hate groups, including the African American Defense League, because he “liked” some of their Facebook pages. Five days prior to the Dallas shooting, Johnson posted a “rant” against white people on Facebook. Four days after Johnson’s post and one day before the Dallas shooting, the African American Defense League said that it was “time to act.” These allegations form the basis of Plaintiffs’ secondary liability claim under the ATA. II. The ATA authorizes civil actions for “[a]ny national of the United States injured in his or her person, property, or business by reason of an act of international terrorism.”[6] The ATA initially provided a civil cause of action against only the perpetrator of the terrorist act.[7] There was no cause of action against a person or organization that assisted the person or persons who committed the act of international terrorism, i.e., no “secondary liability.”[8] But, Congress enacted the Justice Against Sponsors of Terrorism Act (“JASTA”)[9] in September 2016, expanding ATA civil liability to include secondary liability.[10] Since JASTA was enacted, a plaintiff injured by (1) an “act of international terrorism” that is (2) “committed, planned, or authorized” by a designated foreign terrorist organization (3) may assert “liability . . . as to any person who aids and abets, by knowingly providing substantial assistance, or who conspires with the person who committed such an act of international terrorism.”[11] Plaintiffs argue that the Dallas shooting was an act of international terrorism committed, planned, or authorized by a foreign terrorist organization because Hamas allegedly used Defendants’ social media platforms from outside the United States to radicalize and recruit Johnson to commit the Dallas shooting. Defendants argue that they cannot be held liable for Retana’s injuries for two reasons: First, Johnson’s mass shooting was not an “act of international terrorism,” as required to maintain a cause of action under 18 U.S.C. § 2333(a), (d); second, Plaintiffs have failed to allege sufficiently that Defendants knowingly provided substantial assistance to Hamas, as required to hold Defendants secondarily liable under 18 U.S.C. § 2333(d)(2). Essentially, Defendants counter that Hamas was not involved in the Dallas shooting; rather, that Johnson acted by himself. A. An act of international terrorism is one that “occur[s] primarily outside the territorial jurisdiction of the United States, or transcend[s] national boundaries.”[12] We cannot conclude that the Dallas shooting transcended national boundaries. We sympathize with Plaintiffs, but this shooting was committed by a lone shooter entirely within the United States. He might have been radicalized in part by Hamas,[13] but Hamas did not plan the shooting or even take credit for it. In Crosby v. Twitter, Inc., by contrast, the Islamic State of Iraq and Syria (“ISIS”) did take credit for a mass shooting, but the Sixth Circuit still held that Twitter was not secondarily liable under the ATA.[14] Plaintiffs’ assertions are even more attenuated than the facts in Crosby. Here, Hamas did not claim credit for the shooting after it occurred. Neither did it order the shooting according to Plaintiffs’ second amended complaint. Johnson was a self-radicalized shooter who merely “liked” the Facebook pages of “black separatist hate groups” that had communicated with Hamas. And, while Johnson met with Ms. X and indicated that he sympathized with Hamas’s objectives, that occurred two years prior to the Dallas shooting. Even considering this weak temporal proximity, we cannot infer that Hamas knew about or was responsible for the Dallas attack. Simply put, Hamas did not commit the Dallas shooting; Johnson did. The shooting did not “occur primarily outside” the United States or “transcend national boundaries,” so it was not an “act of international terrorism.”[15] There is no qualifying “act of international terrorism,” so Plaintiffs do not have a cause of action under § 2333(a). B. For the same reasons, Plaintiffs have not sufficiently alleged that Defendants “knowingly” and “substantial[ly]” assisted Johnson or even Hamas.[16] Aiding and abetting liability under § 2333(d) “focuses on the relationship between the act of international terrorism and the secondary actor’s alleged supportive conduct.”[17] The causal-connection requirement was articulated in Halberstam v. Welch, a D.C. Circuit case that Congress identified as providing “the proper legal framework” for secondary liability.[18] Halberstam identified three factors for determining secondary liability: [T]he party whom the defendant aids must perform a wrongful act that causes an injury; (2) the defendant must be generally aware of his role as part of an overall illegal or tortious activity at the time that he provides the assistance; and (3) the defendant must knowingly and substantially assist the principal violation.[19] The Halberstam court then identified six factors of “how much encouragement or assistance is substantial enough” to satisfy the third factor: (1) the nature of the act encouraged; (2) the amount of assistance given by the defendant; (3) the defendant’s presence or absence at the time of the tort; (4) the defendant’s relation to the principal; (5) the defendant’s state of mind; and (6) the period of the defendant’s assistance.[20] The Second Circuit analyzed these factors in Linde v. Arab Bank, PLC.[21] The plaintiffs in Linde were survivors or relatives of victims of three terrorist attacks perpetrated by Hamas in Israel.[22] They sued Arab Bank, claiming that it was liable under the ATA for aiding and abetting an act of international terrorism.[23] The court held that secondary liability could not be concluded as a matter of law because there was sufficient evidence for the jury to decide that issue.[24] The court in Linde did, however, analyze the Halberstam factors related to whether the defendant “knowingly” and “substantial[ly]” assisted Hamas in committing the attack.[25] It noted that “aiding and abetting an act of international terrorism requires more than the provision of material support to a designated terrorist organization“; it requires “awareness.”[26] The court noted that [t]here is some record evidence that might permit a jury . . . to infer the requisite awareness. For example, certain communications dating from as early as 2001, i.e., before the attacks here at issue, could have alerted the bank that the transfers being requested therein were payments for suicide bombings.[27] But, on remand, the court in Linde left that decision to the jury.[28] The Linde court “reach[ed] the same conclusion as to the substantial assistance element of aiding and abetting.”[29] It did note, however, that “the substantiality inquiry for causation is not identical to the substantiality inquiry for aiding and abetting”: “[A]iding and abetting focuses on the relationship between the act of international terrorism and the secondary actor’s alleged supportive conduct.”[30] Here, there was no relationship between Hamas (vis-à-vis Johnson’s actions) and Defendants as there arguably was in Linde. Neither was there a relationship between Johnson’s actions and Hamas. Neither Hamas nor Defendants can be tied to Johnson’s act of shooting: He merely “liked” “black separatist hate groups’” online Facebook posts and met with Ms. X to express his commitment to Hamas’s goals in Palestine. Neither is there any indication in Plaintiffs’ second amended complaint, other than conclusional statements, that Defendants were “generally aware” of the role that Hamas allegedly played in the Dallas shooting.[31] The shooting was committed by a self-radicalized “lone wolf,” viz., Johnson, not by Hamas.[32] The district court was thus correct in concluding that Defendants were not secondarily liable for aiding and abetting an act of international terrorism. Plaintiffs next assert that the district court erred in using the “direct relationship” test for secondary liability. The district court relied on the Ninth Circuit’s Fields v. Twitter decision when it analyzed Plaintiffs’ secondary liability claim.[33] But the district court also held that Plaintiffs did not demonstrate secondary liability by using their preferred standard of proximate cause. We agree with the district court. As that court correctly held, “Plaintiffs fail[ed] to establish a proper connection between Hamas and the shooting.” To Plaintiffs, the correct test for secondary liability is proximate cause, which would only require that the “alleged injuries proximately flow from the principal’s terrorist attack, not the secondary actor’s supportive conduct.” But this standard still requires that Hamas play a role in the attack.[34] Hamas did not violate the ATA by assisting Johnson in committing the Dallas shooting. In fact, Hamas provided no assistance to Johnson whatsoever. Further, Defendants could not have been aware of Hamas’s role in the Dallas shooting because Hamas played no role in that shooting. Neither did Defendants. We reject Plaintiffs’ proximate cause argument.[35] In sum, at the Rule 12(b)(6) stage, Plaintiffs did not sufficiently allege that Defendants “knowingly” and “substantial[ly]” assisted either Johnson or Hamas in carrying out the Dallas shooting.[36] Defendants are not secondarily liable for the Dallas shooting or for Retana’s injuries. III. We hold, based on Plaintiffs’ allegations, that the Dallas shooting was committed solely by Johnson, not by Hamas’s use of Defendants’ Internet services and social media platforms to radicalize Johnson. It was therefore not an “act of international terrorism . . . committed, planned or authorized” by a foreign terrorist organization.[37] We also hold that Defendants did not “knowingly” and “substantial[ly]” assist Hamas in the Dallas shooting, again because the shooting was committed by Johnson alone and not by Hamas either alone or in conjunction with Johnson. The district court was correct in concluding that Defendants are not secondarily liable under the ATA. * * * The district court’s judgment is AFFIRMED.
