cheering crowd in December 2018. That raises the stakes for conflict. "The United States is not seeking a military confrontation, and are certainly not soliciting international support for any provocation," Frey said. "With that said, while the intent of our presence is deterrence and stability, we are prepared to defend (coalition) member nations' interests from attacks in the maritime domain."
But it won't be just the United States involved if things spin out of control, nor will it likely be confined to the high seas.
THE MILITARIZED GULF
Since the 1980 Carter Doctrine, the U.S. has vowed to use its military power to defend its interests in the oil-rich Persian Gulf. That saw America enter the "Tanker War" toward the end of the 1980s Iran-Iraq war, in which U.S. naval ships escorted reflagged Kuwaiti oil tankers. It culminated in a one day naval battle between Washington and Tehran, and also saw America accidentally shoot down an Iranian passenger jet, killing 290 people.
The 1991 Gulf War, in which a U.S.-led coalition expelled Iraqi dictator Saddam Hussein's troops from Kuwait, further cemented America's presence, as did its later wars in Afghanistan and Iraq.
"The Gulf states have long sought to give external nations a stake in their security and have done so through basing agreements and lucrative arms sales," said Wasser, the RAND analyst. "This buildup is likely to continue because the Gulf states see it as a net gain for their security."
And it hasn't just been the Americans in recent years boosting their presence. The French run their own naval base out of Abu Dhabi, the Emirati capital. The British, who withdrew their forces from the Gulf in the 1970s, recently reopened a naval base in Bahrain. Even Turkey under President Recep Tayyip Erdogan opened a military base in Qatar.
For Iran, it can only look at the wider buildup with suspicion, especially as the U.S. and its coalition bring more warships to the region. While the U.S. and the U.K. had no choice but to respond to the Iranian attacks, their increasing presence can heighten tensions, said Michael Stephens, a senior research fellow who focuses on the Mideast at London's Royal United Services Institute for Defense and Security Studies.
"When you change the chessboard, you are effectively permanently changing the conditions under which you're operating," Stephens said. "How you cannot make that look like an escalation is anyone's guess because it is an escalation."
Iran itself hasn't sat still. The Guard, a paramilitary force answerable only to Supreme Leader Ayatollah Ali Khamenei, pilot speedboats through the Strait of Hormuz and run drills practicing swarming larger warships. It possesses shore-to-ship missiles. It also, according toU.S. officials, has special forces capable of sneaking up on unsuspecting ships to plant explosive mines.
The "rules" that govern military confrontations in the Persian Gulf seem to be changing, Stephens said, with the growing U.S. Navy operation, Iran's willingness to seize and allegedly attack ships, and the collapsing nuclear deal pushing Tehran toward drastic action.
"They're very good at trolling politically. They're very good at trolling tactically," he said about Iran's leadership. "As long as it doesn't spark a conflict, they kind of come out on top. That's how it works."
THE DANGERS AHEAD
One of the immediate dangers is in the response to Iran itself. During the Somali piracy crisis of the 2000s, the rush of navies to the region saw fishermen wrongly targeted for attack in at least one incident, said Salvatore R. Mercogliano, a former merchant mariner and associate professor of history at North Carolina's Campbell University.
Adding additional forces, especially those that may not respond to a single command and exercise different rules of engagement, could raise the risks of a conflict, Mercogliano said. Trying to run convoys of ships through the areas also would slow down traffic and delay shipments. Meanwhile, the Guard's small fast boats easily can be missed among the fishermen and traditional dhow ships moving through the busy waters.
"It is a very difficult area to track any traffic just due to the huge amount of numbers in that area," Mercogliano said. "If you only have a few ships on patrol, a few air assets, a few drone assets, it's very easy to get lured one way or another and miss something."
Meanwhile, U.S. authorities warn that ships in the region have reported "spoofed bridge to-bridge communications from unknown entities falsely claiming to be U.S. or coalition warships." Ships also have reported interference with their GPS systems, according to the U.S. Transportation Department's Maritime Administration. That could see ships accidentally enter Iranian territorial waters.
For international business, the risks could be clearly seen after crude oil prices jumped nearly 4% after the June limpet mine attacks in the Gulf of Oman. Even though the majority of the oil and natural gas passing through the Strait of Hormuz now heads to Asia, prices could spike again.
Insurance premiums for shipments shot up after the June limpet mine attacks by 10%, with additional war-risk premiums costing around $100,000, according to the market data firm Refinitiv.
For mariners in the region, the Strait of Hormuz has been declared a temporary extended risk zone, qualifying them for a bonus and higher death and disability coverage. And while the mariners may be on Western-owned or Western-flagged vessels, many come from poorer countries in Eastern Europe or Asia. The 23 crewmembers aboard the Stena Impero, the British-flagged oil tanker seized by Iran on July 19, are Filipino, Indian, Latvian and Russian.
"The normal seafarers are the ones being caught up in this geopolitical game," said Jacqueline Smith, the maritime coordinator for International Transportation Workers' Federation.