A series of bombings in Sri Lanka show the Islamic State retains a deadly “virtual caliphate” despite losing the territory the organization held at peak strength, according to FBI Director Christopher Wray.

“We worry very much about what is, in effect, a virtual caliphate where terrorist organizations can organize in a way that doesn't require the same kind of physical infrastructure,” Wray told the Council on Foreign Relations.

Wray’s comments Friday lent credence to the Islamic State’s claim of responsibility for the Easter Sunday bombings, although Wray avoided commenting very specifically on the attack, which reportedly killed at 253 Christians and Westerners at churches and hotels on the island. Wray cited the attack a a reminder of the folly of getting “a little bit blasé” about terrorism in the United States.

“There's a difference between being resigning yourself to terrorism as a fact of life and becoming apathetic and numb to it,” he said. “So finding that balance between staying vigilant, staying on the balls of our feet, taking it seriously, and not being consumed or distracted by it is, I think, where we need to be.”

That’s especially true in South Asia, a vital core of the Indo-Pacific region that is teeming with terrorist groups.

“When you take a step back and look at Sri Lanka in the context of jihadist networks operating in the region, it is in the middle of a pretty violent region right now,” Seth Jones, an expert on transnational crime at the Center for Strategic and International Studies, told the Washington Examiner.

Many of those organizations operate out of Pakistan, often undermining U.S. efforts to stabilize Afghanistan after the overthrow of the Taliban government in 2001. Other Pakistani militants target India, in the context of a decades-old struggle over whether India or Pakistan will control the border region of Kashmir; a suicide bombing in India raised international alarm about a potential war between the nuclear-armed neighbors as recently as February.

“We've got so many networks operating in the region, it’s not a huge surprise to me to see an attack occur,” Jones said.

Indian authorities reportedly warned Sri Lanka of an impending threat last month, based on the interrogation of a suspected ISIS militant, although island authorities haven’t explained why they couldn’t stop the attacks.

"I have to specifically mention that that intelligence was not reported to me by the responsible people,” Sri Lankan President Maithripala Sirisena said. "If I had known they had received this intelligence, I could have taken actions accordingly.”

In any case, Wray worries that the difficulty in detecting such threats is growing. “You always hear this phrase about ‘connecting the dots’ in the terrorist arena,” he said. "But a lot of the terrorist plots today are more compact, involving fewer people, a less complicated attack, a shorter period of time — which means fewer dots to connect in the first place.”