The Islamic State’s blitzkrieg advances across large swathes of Iraq have reached the gates of Iraqi Kurdistan and the last week has seen some of the heaviest skirmishes between Kurdish forces, the peshmerga, and the Sunni militants.

Islamic State fighters sought to overpower the ancient Christian and Yazidi settlements around Mount Sinjar, northern Iraq, by using the element of surprise against the peshmerga deployed nearby. By August 7, thousands of religious minorities were fleeing their ancestral lands, trying to escape the Islamic State ultimatum of convert or die. Many were forced to take refuge, and dozens have died, on the barren mountain without food or water.

Seizing several strategically valuable towns, the Islamic State rapidly gained ground on Erbil, the regional capital. Peshmerga forces attempted to push back the militants, but were met with strong resistance. And the jihadist push for Erbil has revealed some weaknesses with the peshmerga, which was thought to be the only effective bulwark against further Islamic State expansion.

Outdated Arms and Inadequate Logistics

While the peshmerga is technically one force, the two main political parties in Iraqi Kurdistan, the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK), both have their own affiliated peshmerga groups. Both KDP and PUK forces have large stocks of Soviet-era weapons, vehicles, and artillery at their disposal.

When Saddam Hussein fell from power, the peshmerga was able to capture significant amounts of the Iraqi army’s battle tanks, howitzers, and sizable stock of small arms. However, a source from within PUK’s peshmerga told VICE News that spare parts for armored vehicles and artillery are scarce, making it hard to maintain offensive capabilities. Then there’s a very real shortage of small arms ammunition and artillery rounds, so the peshmerga forces are starting to lose the upper hand in battle.

The fall of Mosul on June 10 also meant a remarkable equipment upgrade for the Islamic State (then known as ISIS), as the Iraqi government’s roughly 30,000 soldiers abandoned their bases, leaving behind a massive cache of US-supplied armored vehicles and heavy weaponry. This hardware made its way to frontlines in Syria and elsewhere in Iraq, bolstering the Islamic State’s rapid annexation of the Mosul Dam and Sinjar.

Even though the peshmerga can easily outgun the Islamic State in numbers, the Sunni fighters may nullify that advantage with their better-quality weapons and more effective tactics.

Lack of Hands-On Battle Experience

This may seem strange, as the Kurds are well known for their decade-long armed struggle for freedom. The thing is, the higher-ups in both KDP and PUK peshmerga forces fought Hussein and his army back in the day with guerrilla tactics, using Kurdistan’smountainous geography to their own advantage.

Back then, the enemy was a large, conventional army, untrained in guerrilla warfare and with a rigid hierarchy and bureaucratic chain-of-command. These peshmerga cadres are now facing a completely different foe: well-equipped to the task at hand, battle-hardened through years of unconventional fighting in Syria, and made up of smaller units supported by a flexible command chain.

The flat plains of Nineveh province also confront the peshmerga with an entirely different battle terrain than the mountains they have previously trained for.

Furthermore, the peshmerga have not been deployed in active battle in almost a decade. Although there have been build-ups and stand-offs with Iraqi forces around Kirkuk, the young peshmerga soldiers are inexperienced in battle.

In contrast, when Kurdish guerrilla factions of the PKK and the YPG entered the fray from Turkey and Syria to join the fight around Sinjar, the battle was quickly tilted in favor of the Kurds. These groups have battle-hardened soldiers in both their rank-and-file and senior leadership, who have honed their tactical and operational skills in Syrian and Turkish battles for years (in Syria often against ISIS itself). There is no question about it, Iraqi Kurdistan's peshmerga could not have put up with the Islamic State alone.

Finally, when fighting in majority-Arab areas such as Nineveh and Diyala provinces, speaking Arabic is crucial for intelligence gathering and maintaining good ties with civilians. The fact that many young Kurdish peshmerga solders don’t, as Arabic education is no longer mandatory within the KRG, is also a weakness.

Internal Rivalries and Poor Unit Integration

The KDP and PUK haven’t exactly had good relations in the past. They were the main antagonists in a civil war between several Kurdish militias during the mid-1990s, referred to as “the brother killings“ in Kurdish history.

Although a peace treaty was later signed, this strife persists to this day as a mutual mistrust between the parties and extends into the separate peshmerga forces, who are consequently trained separately and do not perform larger joint exercises. This division also shows on the battlefield where poor unit integration and petty rivalries can cause problems.

The temporary loss of Makhmour and the ongoing fighting around Kirkuk is testament to poor coordination and clumsy disposition of forces. Both KDP and PUK forces have clumped together around Kirkuk, for example, while the competition for influence over the oil-rich province seems to have sparked tension between the two parties. When the Islamic State pushed into the greater Sinjar area on August 1, only two smaller peshmerga brigades were stationed there. This obviously put severe strain on their defensive capabilities and they shortly phased into a limited withdrawal.

Adding to the mix of internal rivalries, the Kurdish guerrilla factions from Turkey and Syria have also have strained relations with the KDP. This is mainly because of the power-sharing situation in Rojava in Syrian Kurdistan, where Massoud Barzani’s KDP feels that the YPG is playing an overly dominant role. While they have previously lacked coordination, these groups have been effective in pushing back Islamic State fighters.

It remains to be seen, however, whether or not the Kurdish forces will overcome the inherent divisions that might be blurring their main objective of getting rid of the Islamic State. The coming days may show whether the different factions will unite into a cohesive front, and how much more the Islamic State will push into Kurdish-held territory now it has lost the element of surprise.