Two years ago, Hassan Rouhani was elected president on his promise of constructive engagement with the world, including Iran’s Arab neighbors. After winning the vote, Rouhani told an Al Jazeera reporter, “Our priority is improving our relationship with our neighbors. The states of the Persian Gulf are not only our neighbors, but our brothers.”

That objective has not been met. Instead, mutual accusations of undue interference in the other’s internal affairs have become the norm.

After the nuclear deal, Iran’s relations with the Gulf Cooperation Council (GCC) states top the agenda. To explain the dynamics, GCC attitudes toward Iran must be understood.

Oman is Iran’s only reliable friend on the Arabian Peninsula, and has been since the time of the shah. Sultan Qaboos’ role in the nuclear negotiations was significant enough that upon the deal’s announcement, Rouhani tweeted that he had spoken with Oman’s ruler and thanked him. In an interview with Aftab-e Yazd, Atomic Energy Organization of Iran chief Ali Akbar Salehi said, “When I was foreign minister [2010-13], the United States communicated its intention to hold direct talks with Iran through Oman. After two rounds of negotiations, Sultan Qaboos wrote a letter to [President Mahmoud] Ahmadinejad, saying that he has witnessed the US delegates declaring that they will agree to Iranians enriching uranium inside Iran."