For years, one of the favorite expressions used by officials of the Iranian regime was “strategic depth.” The argument was straightforward: if the Iranian regime was to be defended, it was better to do so not at Iran’s borders but hundreds or even thousands of kilometers away.
The result of this policy was the creation of a network stretching from Hezbollah in Lebanon and the Palestinian Islamic Jihad to Iran-backed militias in Iraq, the government of Syrian President Bashar al-Assad, and the Houthis in Yemen. The Iranian regime called this network the “Axis of Resistance” and presented it as one of the most important symbols of its regional power.
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But the map that once stretched from Tehran to the Mediterranean is no longer what it used to be.
Developments following October 7, the Gaza war, the blows inflicted on Hezbollah, the fall of Bashar al-Assad, and mounting pressure on armed groups in Iraq have, one after another, placed every link of this chain under strain.
A Blow to Hezbollah, the Regime’s Primary Ally
The developments in Gaza and Lebanon dealt a blow to Hezbollah, which for Tehran was not merely a regional ally but the Iranian regime’s most important and best-equipped military arm near Israel.
The group has now suffered military setbacks and is also facing growing domestic pressure in Lebanon to disarm. The issue of placing weapons under the control of the Lebanese government is no longer a marginal topic.
For Tehran, the weakening of Hezbollah means losing part of the deterrence capability it built over decades at enormous cost.
The main blow, however, came elsewhere: Syria.
The fall of Bashar al-Assad may be the most significant development affecting the future of the Iranian regime’s “strategic depth.”
Throughout these years, Syria was more than just an ally of Tehran. Its territory served as the link connecting Iraq to Lebanon and as the primary route for supporting Hezbollah. For this reason, preserving Assad’s rule was far more important to the Iranian regime than simply maintaining a friendly government.
With his fall, one of the most important links in the Tehran-Baghdad-Damascus-Beirut corridor disappeared.
This cannot be viewed merely as a change of government in Damascus. Tehran has lost one of its principal logistical and political routes to the eastern Mediterranean, making the transfer of equipment and support to Lebanon far more difficult than before.
Iraq: The Next Link?
It is still too early to speak of the end of the Iranian regime’s influence in Iraq. Armed groups aligned with Tehran continue to possess military strength, weapons, and political influence. However, conditions there have also changed.
Pressure on the Iraqi government to restrict the activities of armed groups and bring their weapons under official state institutions has increased. The United States has also intensified economic pressure on financial networks linked to some Tehran-backed groups.
Some of these groups have entered negotiations over surrendering or limiting their weapons, while others continue to resist.
Therefore, Iraq has not yet been lost to Tehran, but it is no longer the low-cost backyard it once was.
Yemen: A Proxy That Still Functions
The Houthis are in a different situation. They still retain the ability to attack shipping lanes, regional facilities, and create crises in the Red Sea. They too have suffered devastating blows during recent developments, and years of blockade have weakened their capabilities. Nevertheless, it is not possible to place all of the Iranian regime’s proxy groups in the same category. Tehran’s problem is that the Houthis cannot replace Syria or Lebanon.
The Houthis can create crises in the Red Sea, but they cannot restore the missing link between Tehran, Baghdad, Damascus, and Beirut. That is the crucial difference between today’s situation and that of just a few years ago.
The War That Was Never Supposed to Reach Tehran
The logic of “strategic depth” was to keep war away from Iran’s borders. The regime invested heavily to ensure that battlefronts remained in Gaza, Lebanon, Syria, Iraq, and Yemen—a strategy repeatedly emphasized by Iranian regime supreme leader Ali Khamenei in speeches over recent years. Yet, in the end, exactly what this strategy was designed to prevent occurred: war reached Iran itself, and that war was not only fought in the skies but also in the streets of Iranian cities as the people confronted the regime.
This has happened at a time when the regime no longer enjoys the domestic conditions it once did. The consequences of the January 2026 uprising, the economic crisis, widespread public discontent, and the regime’s lack of legitimacy are weighing heavily alongside external pressure on Tehran.
What has clearly changed is the cohesion and strength of the network that the Iranian regime built over four decades and regarded as its defensive shield.
Syria has been removed from this chain, Hezbollah has suffered severe blows, and the future of Iran-backed groups in Iraq is also under growing pressure.
