Earlier this year, U.S. military commanders in the Middle East were puzzled to note that a dangerous trend of Iranian small boats harassing Navy vessels in the Persian Gulf had suddenly and unexpectedly come to a halt.
And though Iran has announced a show-of-force military exercise in apparent response to a new round of U.S. sanctions that went into effect Tuesday, calm continues to prevail on the waters, the commander of U.S. Central Command told reporters at the Pentagon on Wednesday.
"I think so far this calendar year, we have not seen any incidents we would characterize as unsafe or unprofessional, compared to what we've seen over the last couple of years," Gen. Joseph Votel said. "I don't know if I can explain why that is; I'm glad that's not the case."
The Wall Street Journal first reported in January that after two years of routine harassment of American vessels, including instances in which the U.S. Navy resorted to firing warning shots, the run-ins dropped off in August 2017.
"For whatever reason they're doing that, I hope that continues," Votel said. "I would just highlight that we remain very vigilant in terms of this."
The Defense Department announced last week that it was monitoring a major Iranian naval exercise that began Aug. 2 in the vicinity of the Strait of Hormuz, timed to coincide with the U.S. reimposition of stringent economic sanctions on Iran restricting trade, export of certain products, and the ability to purchase U.S. currency.
In a tweet, President Donald Trump called the measures "the most biting sanctions ever imposed," saying they would prevent anyone who did business with Iran from doing business with the U.S.
While Votel said the scope of the recent Iranian maritime exercise was similar to that of other exercises done in the region, its timing gave it added significance.
"It's pretty clear to us that they are trying to use that exercise to send a message to us, that, as we approach this period of sanctions here, that they have these capabilities," he said. "I think the purpose of any messages we would send would be to highlight to them that we are paying attention, we are very vigilant, we are aware of what's going on, and we remain ready to protect ourselves as we pursue our objectives of freedom of navigation, freedom of commerce and international democracy."
The Strait of Hormuz, which connects the Persian Gulf and the Gulf of Oman, is a key transit passage for the U.S. Navy.
The carrier George H. W. Bush passed through the strait in March 2017, becoming the first carrier to enter the Gulf during the Trump administration. Iranian vessels reportedly harassed the carrier as it made the transit, but did not delay the ship's passage.
On Wednesday, Votel demurred when asked if Iran had the ability to close the Strait of Hormuz if provoked.
"Iran has layered capabilities that include mines, that include explosives ... coastal defense missiles and radars. They certainly have some capabilities there," he said. "But I would just suggest we have capabilities as well."