Iran Is The Best At Making Enemies.

Of course, it’s doubtful Iran will readily accept the results of a Saudi investigation. Not in light of the longstanding tensions between Sunni-dominated Saudi Arabia and Shiite-led Iran, which have escalated in recent days, threatening an even bigger showdown that could roil not only the Middle East but the world.

Iran bans Saudi imports, pilgrimages to Saudi cities

The Sanaa airstrike, and the war of words that followed, come on the heels of Saturday’s mass execution in Saudi Arabia of 47 people, among them prominent Shiite cleric Sheikh Nimr al-Nimr, on terrorism charges.

This act spurred anger in Iran, where protests quickly broke out. The Saudi Embassy in Tehran was attacked and set on fire, prompting Saudi leaders to sever diplomatic ties with Iran.

Several other nations have sided with Riyadh in this growing conflict, including Bahrain — where a Sunni monarch rules over a predominantly Shiite nation — and Kuwait and the United Arab Emirates, both of which recalled their ambassadors to Iran.

Yet Iran has remained defiant, with President Hassan Rouhani on Tuesday lashing out at Saudi Arabia for cutting ties in response to an angry reaction that he called “only natural.”

“Of course, the Saudi government, in order to cover up its crime of beheading a religious leader has resorted to a strange measure and has severed its ties with the Islamic Republic,” Rouhani said during a meeting with Danish Foreign Minister Kristian Jensen in Tehran

“Undoubtedly, such moves will never hide that great crime,” Rouhani added, according to Iran’s state-run Press TV.

On Thursday, Iran acted out once more against Saudi Arabia — this time, economically.

The Iranian Cabinet passed a measure banning the import of all products from Saudi Arabia and prohibiting Iranians from making pilgrimages to the holy cities of Mecca and Medina, the semiofficial Tasneem news agency reported. Millions make pilgrimages each year to those two Saudi cities in rites of passage for Muslims worldwide.

Yemen, like Syria, a proxy battleground for rivals

While Nimr’s execution may have been the tipping point, it’s far from the lone source of tension between Tehran and Riyadh.

In one respect, this discord dates back 14 centuries to when Sunnis and Shiites split over who should succeed the Prophet Mohammed as Islam’s leader.

Today, nearly 90% of the world’s Muslims are Sunni. Still, there are powerful Shiite players in the world, including in Iran and Syria, whose embattled leader Bashar al-Assad is Alawite, a Shiite offshoot.

That’s one reason Iran has been one of Assad’s few notable allies, while Saudi Arabia has given financial aid and weapons to rebels fighting him.

CNN’s Shirzad Bozorgmehr contributed to this report.

By Greg Botelho and Schams Elwazer, CNN