“If they impose sanctions on Iran’s oil exports, then even one drop of oil cannot flow from the Strait of Hormuz.”

After a long week of Iran headlines – US Secretary of State Mike Pompeo laying out the administration’s Iran strategy, Presidents Trump and Rouhani trading implicit threats of war, Iranian Revolutionary Guard Corps-Quds Force (IRGC-QF) Commander Qassem Suleimani addressing Trump by name in a speech – one might be forgiven for mistaking the above as a recent quote.

But that threat is actually from 2012, when Iranian Vice President Mohammad Reza Rahimi decried Obama administration oil sanctions in response to Iran’s nuclear program. Iran’s recent threat to close the Strait of Hormuz is not new, but rather a tactic Tehran has turned to again and again to get what it wants.

About one-fifth of the world’s total oil passes through the Strait of Hormuz, and roughly one-third of tanker traffic squeezes through its two-mile wide shipping lane. The US Energy Information Authority estimates that 18.5 million barrels per day cross the strait, and unofficial numbers calculated a total of 17.2 million in 2017. These staggering figures make clear the importance of stability in the waterway.

So, while IRGC Commander Mohammed Ali Jafari’s promise earlier in July to “make the enemy understand that either everyone can use the Strait of Hormuz or no one [can]” is jarring, it isn’t quite surprising, or even new. That does not mean there is no reason to be concerned, though. Below are several areas to watch should US-Iran tensions escalate around the Strait of Hormuz.

Even higher oil prices?

The reasons the Trump administration would want to keep the strait open are manifold. Uninterrupted shipping through Hormuz means stable oil prices, which in turn contribute to stability in the global economy. Recognizing the importance of the strait, Iran has in the past threatened to close it as a means of pressuring the United States, while the US Fifth Fleet, stationed in Bahrain, views protecting shipping in the strait as one of its primary objectives.

With the threat of US secondary sanctions pushing down Iranian oil exports, oil prices are set to rise in the coming year. To offset this, the Trump administration has pushed Saudi Arabia to increase its production to prevent prices from rocketing upward. The Saudis have duly increased their oil output, though not to the point where they can curb rising prices completely. An earnest Iranian blockade of the strait would therefore drive oil prices up, potentially throwing sand in the gears of the Trump administration’s plans to stabilize prices.

Iran has made this threat multiple times in the past – the United States is prepared for it – and the likelihood of Tehran taking action on this occasion seems low. Blockading the strait would be an escalatory step that would almost certainly elicit an international response led by US maritime forces in the Gulf and cause a military escalation that no party ostensibly wants.

Threat of accidental escalation

That said, Iran can pursue other options to give the United States headaches in the Gulf that do not rise to the level of open conflict. The IRGC-Navy (IRGC-N) “buzzes” US naval craft in the Gulf with its own fast craft and drones regularly, and it’s unclear that diplomatic channels exist to deconflict potential situations. In 2016, the IRGC-N captured US sailors who accidentally strayed into Iranian waters. The Obama administration relied on channels from nuclear talks to manage that particular crisis, but with the recent American withdrawal from the Joint Comprehensive Plan of Action (JCPOA), it is unclear how Washington would be able to communicate with Tehran should a similar incident occur now.

Some analysts view dealing with the IRGC-N’s asymmetric tactics and flaunting of maritime norms as the price of doing business in the Gulf for the United States. But with Iranian Hormuz threats heightening tensions, accidental escalation through a crash or other incident is possible and might be a more likely spark to an international crisis than overt action by either side. Secretary Pompeo’s meeting in Washington this week with Oman’s foreign minister might represent an effort on the part of the administration to re-introduce mediated dialogue with Iran.

Iran threatens strategic waterways, again

Iran’s threats against Hormuz are nearly identical to Iranian-backed forces’ attacks on another strategic waterway astride the Arabian Peninsula. Last Wednesday, Yemen’s Houthi rebels, who receive arms, materiel, and training from Iran, attacked two shipping containers with two million barrel capacity passing by the port of Hudaydah. The Houthis have held Hudaydah, which sits near the Bab al-Mandab, the strait between Africa and Asia where the Red Sea empties into the Gulf of Aden, for months, and the Saudi-led coalition countering them is pushing hard to reclaim it.

In response to last week’s attacks, Saudi Arabia suspended oil shipments through the Bab al-Mandab. That same day, Quds Force commander Suleimani said publicly that “the Red Sea which was secure is no longer secure for the presence of [the] American [military].”

The Saudi decision to suspend shipping may be a measure intended to draw global attention to Iran’s meddling in Yemen rather than an expression of genuine concern over the safety of Red Sea shipments, and oil prices didn’t move much after the attacks. However, sustained uncertainty and geopolitical sparring certainly could affect oil markets over time, and the Houthi cause gives Iran the plausible deniability necessary to continue to harass the Saudis, Americans, and other rivals passing along the Yemeni coast.

What will Trump do?

Although the United States would certainly respond militarily to a strait closure, it would likely act with international partners rather than unilaterally. US officials told CNN that they would encourage US regional partners to take action against Iran, and US Secretary of Defense James Mattis emphasized in recent statements that the international community has worked collectively in the past to address threats to global shipping from Iran. It would be surprising to expect a dissimilar response should threats rise from the rhetorical to the kinetic.

At the same time, the language from Washington and Tehran has oscillated between bellicose and opaque. After the back-and-forth between Trump and Rouhani, President Trump on Monday said that he would be willing to meet in-person with Iranian leadership. Such a meeting seems unlikely to happen any time soon, especially after such heated exchanges, but, at this point, it’s hard to imagine any eventuality being entirely out of the realm of possibility.

Owen Daniels is an associate director with the Middle East Security Initiative in the Atlantic Council’s Scowcroft Center for Strategy and Security. Follow him on Twitter: @OJDaniels.

Image: A military personnel participates in the Velayat-90 war game on Sea of Oman near the Strait of Hormuz in southern Iran December 28, 2011. (REUTERS/Fars News/Hamed Jafarnejad)