After a string of deadly attacks on Shiite neighborhoods in Baghdad, the likely work of the Islamic State group, Iraq's neighbor Iran has made an official promise of help against the Sunni militants. Iran has been running special forces operations against ISIS for some time, and on Tuesday President Hassan Rouhani said Iran would boost its support by providing more military advisers and weapons. The statement came during Iraqi Prime Minister Haidar al-Abadi's visit to Tehran.

Rouhani said Iran had supported Iraq "from the first day and will remain on that path until the last day," according to a report by the official Islamic Republic News Agency. The two countries secured a strong alliance following the U.S. invasion that overthrew Iraqi President Saddam Hussein in 2003. Saddam, a Sunni, ruled over a country that is majority Shia, like Iran. 

"Choosing Iran as my first destination after taking office indicates the depth of ties," Abadi said during the meeting, according to IRNA. "Terrorism is a threat to all regional countries, and we are sure Iran will stand by us."

Ahead of his visit to Tehran, Abadi had ruled out a foreign intervention against IS militants, saying he would rather rely on local militias. But many of those militias, mostly Shiite, are backed by Iran.

The Iranian Revolutionary Guard Corps trained thousands of Shiite militiamen in Iraq in the decade since Saddam was toppled. At beginning of the advance of the Islamic State group, or ISIS, in Iraq in June, Rouhani sent members of Iran's elite Quds Force to help its Shiite ally in Baghdad fight the Sunni militant group. 

In his first visit to Tehran since his appointment, Abadi said Iraq was at war with "terrorists" that were creating deep sectarian rifts between Shiite and Sunni Arabs. Those sectarian tensions have increased drastically since the beginning of the month, with ISIS targeting Shiites directly in its attacks. In the past few weeks, ISIS has killed hundreds of people, many of them Shiite, in suicide and car bomb attacks in Baghdad. 
The most recent round of ISIS attacks took place near the capital, killing 30 people. The deadliest attack occurred when a double car bomb attack hit a restaurant in the Shiite-majority district of Talibiya in eastern Baghdad and killed 19 people. On Monday, a suicide bomber blew himself outside a Shiite mosque during afternoon prayers, killing 17 people. Meanwhile, a triple car bombing hit the Shiite holy city of Karbala, killing 16 people.
Angered by the attacks on Shiite holy sites and neighborhoods, Iran is increasing its presence in Iraq. 

Rouhani said in July that Iran would consider working with the U.S. in Iraq to defeat ISIS, but it is still not clear whether the two, which have many conflicts and no diplomatic relations, are coordinating their efforts on the ground.