Iraq’s Kurdish forces are entering a new era following the withdrawal of US-led international forces that had been in the country to fight ISIL (ISIS).

On Wednesday, the United States announced the formal end of Operation Inherent Resolve, its name for the 12-year-long campaign to defeat ISIL, and the completion of the withdrawal of its military forces from Iraq.

Other partners in the war against the armed group also withdrew from Iraq, in accordance with a September 30 deadline set by Washington and Baghdad two years prior.

For years, Iraq’s Kurdish forces – known as the Peshmerga – have relied on close military support from coalition forces, and the US in particular, to safeguard their autonomy and defend against ISIL.

Their withdrawal has posed new political and security challenges for Iraq. Where does the Peshmerga stand today?

The challenge of unification

Days before the coalition’s withdrawal, on September 21, the Erbil-based Kurdish Regional Government (KRG) – which presides over Iraq’s semi-autonomous Kurdistan region – announced that it had finally merged Kurdish armed factions into a unified fighting force.

In his speech at the ceremony marking the event, KRG President Nechirvan Barzani characterised it as a major national step towards consolidating the region’s institutions.

“Kurdistan needs one force, one ministry, and one command,” he said. “The Peshmerga must be a national force, free from party interference and disputes. Today, we take a major step towards achieving this goal.”

Barzani announced that the militias affiliated with his Kurdish Democratic Party (KDP) and its historic rival Patriotic Union of Kurdistan (PUK) were now under one structure. The KDP and PUK represent the two dominant Kurdish Iraqi factions.

Zeidon Alkinani, a Middle East political analyst and founding director of the Doha-based Arab Perspectives Institute, told Al Jazeera that the unification would help stabilise Iraq.

“Iraq’s most damaging rivalries have been within communities, intra-Shia and intra-Kurdish, not between them,” he said.

He says reducing the role of the Erbil-based KDP and the Sulaymaniyah-based PUK party structures within the Peshmerga “strengthens Iraq’s stability and gives Erbil firmer legal footing with Baghdad”.

However, the work is far from finished. Barzani, in his speech, warned that the unification marked the start of a phase that “may be even more difficult” than past Kurdish struggles, requiring the Peshmerga to stand above party loyalties.

“The test is whether [unification] survives, given the persistence of two geographically distinct commands”, Alkinani says.

Retired Lieutenant General Jabbar al-Yawar, former secretary general of the Ministry of Peshmerga in the KRG, told Al Jazeera that these parties were embroiled in a number of political disputes, including governance of Kurdistan and relations with Baghdad.

These disputes, he says, could extend to military institutions if the forces remain tied to political parties.

Readiness

On the ground, the Ministry of Peshmerga insists that its forces are ready for the new era.

Spokesperson Major General Othman Mohammed told Al Jazeera that the Peshmerga “has always been on full alert,” touting its role in repelling the ISIL in 2014 despite having limited means.

He pointed to the relationship between the Peshmerga and Iraq’s other security forces, noting that commanders from both sides enjoyed very good cooperation and coordination.

This coordination has become more important now that the international coalition has ended its mission, with Iraqis now relying on their own capabilities to detect and stop ISIL activity.

Despite this readiness, Mohammed Salih, a non-resident senior fellow at the US-based Foreign Policy Research Institute and an expert on Iraqi and regional affairs, says there is “considerable uncertainty and concern among Kurds surrounding the US withdrawal”.

Many are asking whether the departure of US troops means the end of Washington’s commitment to Kurdish security, he told Al Jazeera, given that the US has been “a key security guarantor for the Kurdistan region for the past three decades”.

Importantly, the US took with it key air defence systems when it withdrew, creating serious concern for Erbil, which has come under several drone and missile attacks since the start of the US war on Iran.

Balanced relations

Erbil has signalled its intention to continue cooperating with Baghdad as before, under Iraq’s federalist framework.

The day after coalition forces withdrew, KDP leader and former KRG President Masoud Barzani touted “very strong coordination with the Iraqi federal government to confront any kind of threat or danger, whether it comes under the name of ISIS or any other name”.

In Baghdad, he backed the federal government’s efforts to fight corruption, disarm Iran-aligned militias and settle outstanding disputes with Erbil under the constitution.

Iraqi federalism and unity “depend on communication, coordination and respect for the rule of law among political parties, not on foreign troops”, Alkinani of the Arab Perspectives Institute said, in relation to the coalition withdrawal.

Baghdad faced a dilemma when Washington demanded it disarm Iran-aligned Iraqi armed groups. The armed groups refused, pointing to the US presence in Iraq even as it waged war on Iran.

The withdrawal may help the cause of federalism by removing this justification, he said, “but only if Iraqis replace it with dialogue and law rather than force”.