Undated handout archive photo by the Norwegian shipowner Frontline of the crude oil tanker Front Altair, released June 13, 2019. NTB Scanpix | Reuters

DUBAI — Iran's economy is crumbling. It's in a region bristling with U.S. military hardware, and it's staring down an American administration that has made clear all military options are on the table. So why would elements within Iran risk blowing up foreign merchant tankers in their own backyard? It's a question many people were asking even before the Pentagon reported Thursday that an American drone was shot down over the Strait of Hormuz. Iran claimed responsibility for that strike. It's crucial to note that the culprit behind attacks on two commercial tankers last week has not been conclusively proven. On June 13, explosions crippled the Japanese Kokuka Courageous and the Norwegian Front Altair, forcing their crews to abandon ship. The U.S. and the Saudis say Iran is behind the attacks, while the U.K. says they're "almost certain" of the same; Iran vociferously denies it. But video footage and photographs from U.S. CENTCOM provides what a range of security experts say is credible evidence of Iranian responsibility. Here's a look at what might've driven elements within Iran, particularly its Revolutionary Guard Corps, to carry out the tanker attacks.

1. Iran 'has nothing to lose'

"Iran has probably arrived at the conclusion that it has less to lose from acting this way than from doing nothing," Aniseh Tabrizi, a research fellow and Iran expert at London's Royal United Services Institute, told CNBC via phone Tuesday. "There is a gamble behind it that wasn't there before, which is: 'If other countries retaliate, we are willing to take the risk because we have really nothing to lose at this point'," Tabrizi described. "And that is a dangerous way to feel." Iran's economy is expected to shrink by 6% this year, after having contracted 3.9% last year, the International Monetary Fund says. By contrast, it clocked 3.8% growth in 2017, before the Trump administration re-imposed economic sanctions after withdrawing from the 2015 nuclear deal that offered the Islamic Republic relief from prior sanctions. The combination of hard-hitting sanctions, particularly on the country's oil exports, and years of economic mismanagement have led to skyrocketing unemployment and inflation headed toward 40%. "The more the U.S. maximum pressure policy succeeds in driving the Iranian economy into the ground," Ali Vaez, Iran Project Director at Crisis Group, told CNBC, "the less risk averse the Iranians will become and the more aggressive they're likely to be."

2. Calling Trump's 'bluff'

"It's all about careful calibration and plausible deniability," Hussein Ibish, a senior resident scholar at the Arab Gulf States Institute in Washington, told CNBC. Iran's tactics, experts say, are designed to disrupt but not provoke a military response. So far, attacks have specifically avoided civilian deaths and environmental damage like an oil spill. Instead, the Revolutionary Guard or its naval equivalent may be sending the message that it's capable of undermining U.S. and Arab Gulf states' interests in the region. And if they feel they can get away with it, it's because they're banking on President Donald Trump not wanting to actually start a war. "Ultimately, Iran's intention is to call President Trump's bluff," says Ibish.

Imagery taken from a U.S. Navy MH-60R helicopter that allegedly shows Islamic Revolutionary Guard Corps Navy after removing an unexploded limpet mine from the M/T Kokuka Courageous. US Navy

And indeed, Trump told Time Magazine in an interview this week that he views the tanker incidents as "very minor," suggesting that attacks of this nature are not worth going to war over. The administration has already gone almost all out on economic sanctions, "So the repercussions are virtually nil," says Ibish. "That's one reason why Iran is taking these actions: they have nothing to lose except getting into a war they don't want, but which Trump does not want either. And that's what they're testing right now," he said.

3. 'Hit them where it hurts' — oil and shipping security

Iranian leaders have often threatened that if they can't export their oil, neither will anyone else. And last week's suspected attacks took place near the Strait of Hormuz, the narrow waterway for 30% of the world's seaborne oil traffic. Combined with the four tankers allegedly sabotaged off the United Arab Emirates' coast of Fujairah on May 12, last week's attacks "appear to be part of a systematic Iranian effort to demonstrate that peace and security in the Gulf is contingent on its own economic stability," political consultancy Eurasia Group said in a June 13 briefing.

They do not seek a war, exactly, but they are obviously willing to risk one in order to get out of an impossible conundrum. Hussein Ibish senior resident scholar, Arab Gulf States Institute in Washington

Iran's Supreme Leader Ayatollah Ali Khamenei "has made threats to the Americans saying we're going to hit where it hurts — and the hydrocarbon lifeline of the Strait of Hormuz is what hurts," Andreas Krieg, a lecturer at the School of Security Studies at King's College London, told CNBC. Targeting commercial tankers and oil traffic hurts Iran as well, Krieg says — "but the Iranians have their backs against the wall, and there's very little they can lose because they're already in a state of absolute loss after the imposition of the maximum pressure sanctions regime."

4. Deterrence and leverage

"If the Iranians were indeed behind this then I think the main motive is to deter the U.S. from further ratcheting up pressure on Iranian oil exports," says Crisis Group's Vaez. "But this also has the added benefit of ransoming the oil market which will jack up the price on shipping insurance premiums, and this will allow the Iranians to compensate to a certain extent for the loss of their oil exports as a result of U.S. sanctions."

And for Iran, this type of unconventional warfare also demonstrates that it can wreak significant damage on Western interests at a fairly low financial cost, something that can't be said for the U.S. military. "The Iranians have a lot more flexibility and political will to operate in this area than the Americans," says Krieg. "The problem with the Americans is there is no political will, there's limited capability to strike back, and the costs are exponentially higher."

5. History