Among the agreements signed in August when the U.S. president hosted the leaders of Armenia and Azerbaijan in Washington was the “Trump Road for Peace and Prosperity” (TRIPP). Intended to link Azerbaijan proper with its ethnic enclave of Nakhchivan via southern Armenia, the TRIPP has the potential of transforming security and connectivity in the South Caucasus and beyond.

Iran regards the TRIPP negatively, fearing it will jeopardize its land border with Armenia, a long-time ally. But Tehran may not be able to do much to prevent its realization due to other geopolitical constraints and fear of further antagonizing Washington.

In the wake of the August summit, Iran’s Ministry of Foreign Affairs talked of “the negative consequences of any form of foreign intervention, especially near shared borders.”

For the Islamic Republic the TRIPP is an uncomfortable development. For decades, Azerbaijan has relied on the Aras Corridor — which transits northern Iran — to reach Nakhchivan. This route has been operational since the 1990s when the first Nagorno-Karabakh war ended with Azerbaijan’s defeat. The corridor expanded in 2023 with an agreement between Baku and Tehran on the development of more road and railway infrastructure. The TRIPP, however, would deprive Iran of not only lucrative transit fees but also an important geopolitical lever over Azerbaijan, with which Tehran has often had tense relations in part because of Baku’s ties to Israel.

Iran has long criticized potential changes to state borders in the South Caucasus and has supported Armenia’s territorial integrity against external interference. Iran also opposed an earlier version of the TRIPP corridor, the so-called Zangezur route, promoted by Azerbaijan and Turkey. The reasoning in Tehran maintains that if any version of a corridor under extraterritorial control runs through Armenia, the Islamic Republic will lose its single friendly entry point into the South Caucasus. This would also mean that Iran would not be able to access Georgia’s Black Sea ports to reach the European market.

There are still multiple questions remaining about how the TRIPP will be operated. But Tehran remains concerned about any U.S. or other hostile presence along its borders. The Armenian leadership has tried to assuage Iran’s fears, stating that the agreement will be beneficial to the region and that Iran will not be detached from Armenia given the fact that Yerevan will retain administrative control over the TRIPP and that U.S. troops will not be involved.

So far, these arguments have not proved persuasive to Tehran. In a swift reaction to the TRIPP, Iranian President Masoud Pezeshkian visited Armenia on August 19 with a large delegation. The visit, aimed at boosting bilateral ties across political, economic, cultural, and social fields, led to a signed joint statement and 10 cooperation documents. But fear of potentially losing a land connection with Armenia has remained a major issue. The Iranian president commented that Iran’s “concerns regarding the presence of third-party forces near our common borders must be fully addressed.” At a press conference, Armenian Prime Minister Nikol Pashinyan argued that roads passing through Armenia would remain under the exclusive control and sovereignty of Armenia.

The TRIPP project also affects competition over evolving connectivity in the South Caucasus. Iran has long pursued transit routes to the Black Sea and Russia. The International North-South Transport Corridor (INSTC) from Russia to Iran has seen some major success, while transit via Armenia has always lagged and needed more investment in road and railway infrastructure. But the TRIPP might be pushing Tehran to act more boldly. One of the agreements signed in Yerevan was on the construction of a second Norduz Bridge between the two countries, as well as agreements to complete the railway connection from the Persian Gulf to the Black Sea.

Iran is unlikely to make any brusque move to confront the TRIPP as long as the project does not pose a direct threat to the security of the Islamic Republic. Tehran is constrained by wider geopolitical limits. The promotion of the TRIPP has coincided with the weakening of Iran’s position in the Middle East following the 12-day war with Israel, which was joined at the end by the U.S. Moreover, the degradation of the Axis of Resistance — the Tehran-backed transnational network of non-state actors — has further boxed in Iran’s ambitions across the region. With the crisis unresolved over Iran’s nuclear program despite the massive Israel and U.S. strikes, Iran is unlikely to act proactively to openly undermine the TRIPP.

Iran’s decline in regional influence has left a vacuum in the Middle East that has been partially filled by Turkey, which has expanded its engagement with Syria and Iraq. Turkish influence is expanding in the South Caucasus as well. The TRIPP is widely seen as benefiting Ankara more than any other big power involved in the area. Indeed, in the wake of the corridor deal announced in Washington, Ankara announced the construction of the Kars-Iğdır-Aralık-Dilucu railway, which would link Turkey’s railway hub of Kars with Nakhchivan. Given the alliance between ethnic Turkic cousins in Ankara and Baku, the TRIPP would only enhance Turkey’s influence in the South Caucasus. The route would diversify connectivity in the South Caucasus and allow Turkey to reach the Caspian basin and Central Asia via two corridors: one through Georgia, the other via Armenia.

Fear of Turkish influence is also rising in Russia, which, like Iran, has historically sided with Armenia in its disputes with Azerbaijan. This trend is likely to accelerate the alignment between Russia and Iran over what happens in the South Caucasus. Both oppose a U.S. presence there as well as growing Turkish influence. On August 25, the Russian and Iranian presidents held a phone call in which they specifically discussed the South Caucasus. Expansion of the INSTC is one likely response by Moscow and Tehran, and growing cooperation on security in the region could be another element of bilateral engagement.

Emil Avdaliani is a research fellow at the Turan Research Center and a professor of international relations at the European University in Tbilisi, Georgia. His research focuses on the history of the Silk Roads and the interests of great powers in the Middle East and the Caucasus.