A House subcommittee yesterday tried to shed light on the alleged Iranian plot to assassinate the Saudi ambassador to the U.S. and discussed how Washington should react.

The House subcommittee on counterterrorism and intelligence got some partial answers, but more questions remain. All the expert panelists who testified agreed that even though apparently implausible, such a plot would have required the authorization of the Iranian spiritual leader, the Ayatollah Khamenei.

But that in itself poses a question — why would the Iranian leader take the risk of triggering a direct U.S. military response (which would surely have been the result had the plot succeeded)?

This alleged plot is starting to remind me of Winston Churchill’s famous remarks about Russia: “a riddle, wrapped in a mystery, inside an enigma.”

For Matt Levitt, a counterterrorism expert at the Washington Institute for Near East Policy, the approach to the Mexican drug cartel would have provided the Quds force — accused of masterminding the alleged attack — with deniability. The force, an elite unit of the Revolutionary Guards, is used to operating through proxies, and the Zeta cartel would simply be another, he contended. Retired Marine Corps Col. Timothy Geraghty said that Iran and its proxies have a 30-year record of attacking America, for which they have a profound hatred, and are now “intent on attacking us in the homeland.”

Quds has suffered several recent failures, Levitt pointed out. In addition to foiled Quds plots run with Hezbollah in Azerbaijan and Turkey, Iran has been the victim of the Stuxnet worm that attacked its nuclear facilities, and nuclear scientists have been targeted for assassination.

So was this plot an “act of desperation” by a country reeling from the impact of sanctions, as former Reagan administration Pentagon official Larry Korb suggested at yesterday’s hearing?

Despite some colorful language from retired Gen. John Keane, who said “we’ve got to put our hand around their throat now,” none of the panelists, including him, urged military retaliation. They called for a panoply of escalation, including covert action and ramped-up sanctions to send a message to the Iranian leadership that it had crossed a “red line” by seeking to assassinate the Saudi envoy on American soil. These could include targeting the Iranian central bank.

Yet all of these elements seem to be already part of the Obama game plan. This poses another question: Why is the Obama administration talking about punishing Iran before the court case of the Iranian-American suspect has reached a conclusion? He pleaded not guilty in a New York court this week.

And there are at least two other issues that need to be elucidated — a confirmation of the suspect’s relationship to the Quds force, and the methods used by the Drug Enforcement Administration in what could be an entrapment operation. So far, much of this plot riddle/mystery/enigma are not in the public domain. And we’ll have to wait until Dec. 21 for the trial of the alleged plotter to resume.