I don't know who is responsible for the so-called "sonic attacks" on U.S. diplomats in Cuba, but I have some ideas.

First off, it's worth noting what White House chief of staff, John Kelly, added to the story, Thursday, when he stated, "We believe the Cuban government could stop the attacks on our diplomats."

The attacks, an audio representation of which the AP released on Thursday, have affected around two dozen U.S. diplomats and a number of Canadians, leading to symptoms including extreme headaches, speech difficulties, and hearing loss.

Related: US expels 15 diplomats as Cuba attack toll rises

I think Kelly's comment is notable for two reasons.

Most obviously, as chief of staff, Kelly is entitled to the highest-level intelligence in the U.S. government. Kelly thus knows everything that the U.S. intelligence community knows about the sonic incidents in Cuba. But Kelly's comment wasn't just interesting in its content, but also in its delivery. After all, Kelly paused to consider his words before answering. While it might seem like I'm stretching here, when a politician pauses before speaking about sensitive national security issues, it's often because they want to avoid leaking any U.S. intelligence indicators.

In turn, by associating the attacks with the Cuban government, Kelly suggests the U.S. confidently believes that Cuba knows who is responsible for the attacks. While it's notable that Kelly didn't say "Cuba must stop its attacks on our diplomats," his words suggest a belief that the Cuban dictatorship has some culpability.

What might that culpability entail?

It's very hard to say, but to me, three possibilities stand out.

One is that a group of rogue Cuban intelligence officers is attempting to drive the U.S. out of Cuba. As John Schindler has detailed, Cuba's intelligence service, the DI, is both aggressive and highly-skilled. Home to many true believers of Castro's revolution, maybe some officers have taken it onto themselves to purge what they see as excessive U.S. influence in their island nation?

Second, it's possible that someone within the DI is employing cutout agents to attack U.S. diplomats. Cutouts, or deniable intermediaries, are a favored means of conducting intelligence operations wherein detection would bring about significant negative consequences. Correspondingly, Cuban hardliners in the government might believe cutouts would enable them to drive a wedge against U.S. rapprochement while mitigating their vulnerability to retaliation.

The third potential culprit is a foreign intelligence service in Havana. Here, the Russians would be the most likely suspects. That's because Russia would have both the twofold intent of pushing the U.S. out of Cuba and attacking U.S. diplomats (something Russia does aggressively and globally), and the means of action. Russia retains a significant intelligence footprint in Havana, and its officers have the professional skill to pull off this kind of operation. The later attacks on Canadian officials also reek of a Russian effort to throw investigators off the scent.

Still, what unites these three possibilities to Kelly's comments is the fact that Cuban counter-intelligence officers closely monitor their own citizens and foreigners alike. Because of the number of attacks and their timeline, it is credible to assume that Cuban intelligence has knowledge of who was in proximity to the U.S. diplomats when they were attacked.

Ultimately, for the U.S., the challenge of figuring out these sonic attacks is their nature. Whether targeting diplomats in a hotel or a diplomatic residence, whoever was responsible could simply direct a sonic device at a window and then leave it on for whatever time was required to achieve a physical effect. The attacker/s could then leave without a trace.

Regardless, we must assume whoever is responsible has some connection to an intelligence outfit: the attacks are too sophisticated to be the work of thugs or terrorists.