Sen. Diane Feinstein (D-Calif.) at Tuesday’s hearing of the Intelligence Committee. (Karen Bleier — AFP/Getty Images)

But a bit of that backdrop was exposed on Tuesday, when Sen. Dianne Feinstein (D-Calif.) and CIA Director David H. Petraeus mentioned their meetings last week with the head of Israel’s intelligence service, Mossad.

The disclosures came up during an annual threat assessment hearing held by the Senate Intelligence Committee, and the subject was, of course, Iran.

Feinstein, chairman of the committee, followed up her reference to Mossad chief Tamir Pardo by saying that she thought the public deserves to know what inspectors from the International Atomic Energy Agency uncover in their examination of Iran’s nuclear program.

A facts-based debate is critical, Feinstein said, “when you have a situation where one country views this as an existential threat. They believe it’s their survival. They are determined not to let it happen.”

Petraeus replied that he too had met with Pardo, and has been in dialogue with other senior Israeli officials “almost on a monthly basis in the nearly five months that I’ve been in the job.”

The discussions offer a glimpse into the delicate U.S.-Israeli relationship at a time when there are mounting concerns that Israel may launch a military strike — perhaps this year — to stop Iran from acquiring an atomic bomb.

A series of mysterious events — including explosions at Iranian missile facilities, assassinations of Iranian nuclear scientists, and a cyber attack on Iran’s largest uranium enrichment plant — suggest to some that a covert campaign has already begun.

Was the United States involved in those? Has it provided support to Israeli sabotage efforts? Do U.S. officials know whether Mossad carried out those attacks?  If those questions came up in their meetings, Feinstein and Petraeus didn’t say.

U.S. officials including Secretary of State Hillary Rodham Clinton have denied a U.S. role in “any kind of act of violence inside Iran.” The importance of conveying that message was underscored by Director of National Intelligence James R. Clapper’s warning that Iran now seems willing to launch retaliatory terrorist attacks inside the United States.

As to whether Iran actually intends to build a nuclear weapon, Clapper’s answer tracked with what U.S. intelligence agencies have concluded for several years. “They are certainly moving on that path,” Clapper said. “But we – we don’t believe they’ve actually made a decision to go ahead.”