'Final Phase' of Tikrit Assault Begins Backed by US Airstrikes

Iraqi forces have begun what officials say will be the last stage in retaking Tikrit from Islamic State (IS) militants, as the US launches its first airstrikes on the northern city.

Iraqi Prime Minister Haider al-Abadi said late Wednesday that the "final phase" in the operation had begun. Meanwhile, the US announced that it has started launching strikes to support the ground offensive. As of Thursday, American aircraft had launched at least 17 strikes on IS targets in the city, according to a Department of Defense statement.

"The ongoing Iraqi and coalition airstrikes are setting the conditions for offensive action to be conducted by Iraqi forces currently surrounding Tikrit," said combined joint task force commander Lt. Gen. James L. Terry. "Iraqi security forces supported by the coalition will continue to gain territory from [IS]."

Tikrit, around 100 miles north of Baghdad, was seized by IS in June 2014 as the group swept across northern Iraq in a shock offensive. Retaking it would help pave the way for an attempt to oust IS from Iraq's second city of Mosul, which fell at the same time.

A 30,000-strong mixed force of government troops, allied Shia militias, and a smaller number of Sunni tribesmen launched the assault on March 2, with commanders from regional Shia powerhouse Iran taking a leading role. The attackers quickly encircled the city, but progress stalled as the vastly outnumbered IS fighters resorted to guerrilla tactics, and the operation was temporarily paused on March 16. Interior Ministry Mohammed Salem al-Ghabban said at the time that the halt was made to avoid further damage to the city, allow civilians to flee, and minimize Iraqi casualties.

The US had been notably absent from the operation, despite its aircraft carrying out a major and ongoing campaign of strikes targeting IS in Iraq since August. This was partly due to Iraqi leaders pointedly choosing to partner instead with Iran, which trained and equipped many Shia militias involved in the assault. Qassem Suleimani, leader of Iran's elite Quds Force, has also played a widely publicized part in the offensive and is seen locally as leading the operations.

The US also seemed keen to avoid providing obvious support for Iranian-backed forces, which would place it in a somewhat awkward position regionally.

Related: Saudi Arabia-led Airstrikes in Yemen May Inadvertently Be Bringing Sympathy for Houthi Rebels

The strikes came as Washington is now taking part in a last ditch round of talks on Iran's nuclear program, and Sunni Saudi Arabia — a longtime US ally and regional rival to Iran — began bombing Shia rebels in Yemen that are widely believed to be backed by Iran. The Saudi campaign was announced in Washington, and the US is providing logistics and intelligence support. Iranian leaders, including President Hassan Rouhani, have condemned the strikes.

Iran's Lebanese proxy Hezbollah is also playing a major role in supporting Syrian President Bashar al-Assad's forces. Washington wishes to see Assad step down, and has provided rebel groups battling him with weapons and training.

Nevertheless, the US has described Iranian involvement in the Tikrit offensive as "positive." Tehran's presence has also raised concerns about the risk of increased sectarian tensions and violence, however, as Shia militia members assault the predominantly Sunni city.

Shia militias have played a major part in the Iraqi fight against IS, filling the gaps after the spectacular collapse of a significant part of the regular armed forces during the jihadists' June offensive. In some cases, this growth in power and influence seems to have been accompanied by a return to the campaigns of kidnappings and killings last seen during the brutal sectarian violence that almost tore Iraq apart in 2006 and 2007. Rights groups have said the militias operate outside the law, with little or no accountability, and have committed atrocities and war crimes.