Oman, Iran's closest ally in the Persian Gulf region, has signaled that it may be changing course by joining a Saudi-led coalition of Muslim countries fighting terrorism.

Arab news outlets said on December 28 that Oman’s defense minister sent a letter to Saudi Arabia's Deputy Crown Prince Mohammed bin Salman announcing the decision to join the Islamic Military Alliance Against Terrorism.

Gulf sources say the prince will go to Oman in the coming weeks to pave the way for a visit by Saudi King Salman to reestablish security, military, and economic cooperation between the two Gulf neighbors.

Oman’s ties with Saudi Arabia have been strained in the past because of its close relationship with Iran, the kingdom’s biggest regional rival.

By maintaining good relations with Tehran, the sultanate has previously sought to play the conciliator amid worries that a wider confrontation between the two regional powers could threaten its own stability.

Riyadh formed the Islamic alliance against terror a year ago in a move welcomed by Washington as it encouraged greater regional involvement in the global campaign against Islamic State militants in Iraq and Syria.

The coalition includes neither Tehran nor its allied government in Iraq, though it is not explicitly aimed at countering Iran.

Sunni-ruled Saudi Arabia and Shi'ite-led Iran are on opposite sides of Middle East conflicts from Syria to Lebanon, Iraq, and Yemen. The kingdom suspended ties with Iran last year after its embassy in Tehran was attacked in a protest over the execution of a prominent Shi'ite cleric.

Saudi Arabia's Gulf allies also took diplomatic steps against Tehran, who they accused of fueling Shi'ite dissent throughout the region. But Oman, which sits across the narrow Strait of Hormuz from Iran, did not join that effort to isolate Tehran.

That was in keeping with Oman's role as a regional mediator. It played a critical part in making Iran's recent nuclear agreement with world powers possible by facilitating secret talks with the United States that led to the deal.

While other Gulf Arab countries gave money and political support to Iraqi President Saddam Hussein in his 1980-88 war with Iran, Oman maintained relations with Tehran and helped to mediate a cease-fire that ended the fighting.

Some analysts said Oman may be changing course because it has not seen many benefits recently from maintaining good relations with Iran.

The Arab News, which bills itself as the Middle East's leading English-language daily, said Oman's decision to join the Saudi alliance was a "victory" for Saudi Arabia that heralds "a new chapter in regional and Muslim unity."

A newspaper editorial said the move "will isolate those who have been trying to exploit disunity in regional ranks," in an apparent reference to Iran.

Oman’s Foreign Minister Yousef Bin Alawi Bin Abdullah was ambivalent, however, in voicing the nation's current views in an interview with Egypt’s Al-Akhbar newspaper published this week.

He said his country “has common interests with everybody, but each country has its own ways of achieving these interests and goals.”

With reporting by Bloomberg, Reuters, and Arab News

