In the week since twin terrorist attacks in Tehran left 17 people dead, Iran has arrested almost 50 people and pledged to crush domestic terrorist cells. The Islamic State has claimed responsibility for the suicide bombings and gun attacks, the first IS-led attacks inside the otherwise tightly controlled Shi’ite Iran. In the aftermath of the attacks, the Islamic Revolutionary Guard Corps (IRGC) directly pointed the finger at both Saudi Arabia and the United States. The Iranians called the U.S. response “repugnant” because President Trump drew attention to Iran’s funding of terrorism across the Middle East.

The IRGC’s name calling and finger pointing, though, can’t hide the one key takeaway of the Tehran attacks -- where it once thought itself impervious to terrorism, Iran is now paying the price for funding and supporting the Assad regime at home.

More importantly, the incident represents much more than an isolated security breach in Iran’s fight against Sunni militants in the region. If the attack helps embolden those who oppose Iran’s Syrian intervention in the halls of power in Tehran, it could be the catalyst for Assad’s grip on power finally slipping.

Iran’s role in the Syrian conflict on behalf of the Assad regime has been a source of tension among the Iranian ruling elite since at least 2011. Five years on, a power struggle has emerged between President Hassan Rouhani and his reformist allies on the one side, and hard-line reactionaries led by the IRGC and the Ayatollah Khamenei on the other.

Fuel for internal strife has been building up for years. Iran’s commitment to Assad has held firm since the war began, despite a grinding war of attrition and exponentially increasing costs of engagement. The Syrian intervention has cost the lives of more than 700 Iranian troops, and Iran’s principal local proxy, the terrorist organization Hizb’allah, has lost over 1,000 men. In addition to being bloody, the conflict is also costly: Tehran is estimated to be spending $6bn a year on its support for the regime.

The signs of strain have been showing since last year, when Iran’s Foreign Minister Mohammad Javad Zarif fired Hossein Amir-Abdollahian, the man who led Iran’s diplomatic efforts in Syria. His firing provoked angry responses from conservative websites and mass media. Called a “revolutionary diplomat” by IRGC-controlled press outlets, Amir-Abdollahian was regarded by many as the embodiment of “Islamic Revolution diplomacy”, and branches of the Basij militia accused Zarif of yielding to pressure from the U.S. and Arab countries.

Speaking out openly against the intervention, though, is still dicey. Many Iranian ideologues see it as a “war for existence”-- a battle abroad intended to keep a similar war from occurring on Iran’s own soil. Then again, that strategy has not exactly gone according to plan. As early as mid-2014, reports were spreading of ISIS militants crossing the Iraqi border into Iran, with the commander of Iran’s land forces later admitting to the group recruiting among Iranian Sunnis. In March, ISIS operatives in eastern Iraq posted a video on social media networks, with militants vowing to “invade Iran and return it to Sunni control”.

Moreover, Iran faces a much different regional context now that Barack Obama’s awkward courtship has ended and President Trump has replaced it with firm backing of a resurgent Sunni alliance. Since taking office, Trump has played a significant role in shoring up the confidence of American allies who worried Obama was selling out American interests (and theirs) by bending over backwards for the Iranians. Trump’s first trip abroad as President was to Saudi Arabia, where he gave a now-famous speech on the importance of global unity in combating terrorism. That speech unequivocally singled out Iran as a state sponsor of terrorism, sectarianism, and instability in the Middle East and recognized the central role played by Riyadh in stabilizing the region.

Indeed, the President’s assertive stance has all but turned the tables in the Middle East. Longstanding economic and political alliances, once stifled by Obama’s ambivalence, are once again gearing up to defend the Middle East against Iran’s bid for Islamist-minded hegemony. President Trump’s commitment to isolating Iran is coupled with a keenness to challenge foreign policy dogma, putting forth a doctrine of principled realism that rejects the clash of civilizations in favor of building an alliance against terror. As the President himself said: "This is not a battle between different faiths, different sects, or different civilizations. This is a battle between barbaric criminals […] and decent people of all religions who seek to protect it.”

Already, U.S. forces on the ground in Syria are changing the status quo with direct attacks on pro-Assad militia forces and shooting down an Iranian drone. But that support should not be taken for granted. Instead, the $110 billion arms deal announced during Trump’s visit underscores the central role Saudi Arabia will play in fighting terrorism in the region. And while the President clearly stated that “no sudden interventions” will take place under his watch,­ Riyadh was reassured that the bilateral alliance will never be “called into doubt“ again.

Faced with no-nonsense leadership from Washington, Iran’s dreams of ascendancy facilitated by a complicit Obama administration have been firmly dashed. As America finally stands up to its destructive actions in the region, Tehran may finally be forced to rethink its support for tyrants and terrorists. If it does, it won’t come a day too soon.