...The officials declined to describe the unusual contact between the two governments, and whether there had been an Iranian reply. Senior Obama administration officials have said publicly that Iran would cross a “red line” if it made good on recent threats to close the strait, a strategically crucial waterway connecting the Persian Gulf to the Gulf of Oman, where 16 million barrels of oil — about a fifth of the world’s daily oil trade — flow through every day.
Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, said this past weekend that the United States would “take action and reopen the strait,” which could be accomplished only by military means, including minesweepers, warship escorts and potentially airstrikes. Defense Secretary Leon E. Panetta told troops in Texas on Thursday that the United States would not tolerate Iran’s closing of the strait.
The secret communications channel was chosen to underscore privately to Iran the depth of American concern about rising tensions over the strait, where American naval officials say their biggest fear is that an overzealous Revolutionary Guards naval captain could do something provocative on his own, setting off a larger crisis.
“If you ask me what keeps me awake at night, it’s the Strait of Hormuz and the business going on in the Arabian Gulf,” Adm. Jonathan W. Greenert, the chief of naval operations, said in Washington this week...