How significant is Aras corridor for Iran, Azerbaijan to gain Black Sea foothold?

BAKU — Iran and Azerbaijan inched closer to the establishment of the so-called Aras corridor linking the Azeri exclave of Nakhchivan bordering Turkey to the Azeri mainland through Iranian territory — a land corridor that might eventually lead to an Iranian foothold in the Black Sea. 

What raised Iranian hopes for the corridor was a groundbreaking ceremony held on Oct. 6 for a railway linking the Azerbaijani province of Aghband to Iranian territory. Speaking at the ceremony, Deputy Prime Minister of Azerbaijan Shahin Mustafayev said the railway could be extended to Nakhchivan once it's completed. 

Iran has for years been pressing for the establishment of what it dubbed the Aras corridor — named after the river on the Iran-Azerbaijan border —  as an alternative transit route to the so-called Zangezur corridor, which is aimed at connecting Nakhchivan bordering Turkey to the Azeri mainland via Armenian proper. Tehran remains opposed to the Zangezur connection as it would spell a blow to its interests by cutting its only land link of trade and transit to Armenia and thus isolate the entire southern Caucasus, stretching from northern Iran to Georgia on the Black Sea coast. 

Washington strongly opposes the deal, as made clear by Assistant Secretary of State for European and Eurasian Affairs James O’Brien, who at a Nov. 15 congressional hearing said, “[The] transit corridor created with the involvement of Iran will be met with a very strong reaction and will not be a success.”