As the militant Islamic State (also known as ISIS) dominate the headlines, and Australia contemplates humanitarian and military assistance to Iraq, attention has turned to the various groups and factions actively fighting IS in Iraq and Syria.

The IS threat has united the interests of various groups, so we’ve attempted to decode the complex web of actors attempting to keep IS from spreading its self-declared caliphate further into Iraq and Syria.

Australia is going to supply the peshmerga with small arms and munitions. Who are the peshmerga?

The Peshmerga is the official name of the armed forces of the Kurdistan Regional Government. Its members developed a reputation as fearsome fighters in decades-long battles against Saddam Hussein’s armies. The term peshmerga is also used to refer to these Kurdish fighters generally.

The force is divided along political lines into two factions: one aligned with the leftist Patriotic Union of Kurdistan (PUK); the other with the conservative Kurdistan Democratic Party (KDP). The two parties fought a bitter civil war during the 1990s, in which up to 5000 people were killed.

The peshmerga were outgunned and hastily retreated when IS stormed into Kurdish regions in June, but later regained lost ground with the assistance of United States airstrikes, the PKK and the YPG (see below).

The peshmerga forces are the prime recipient of arms and munitions from the West, including from Australia, but some question whether they are up to the task of defeating IS.

“Ultimately, the peshmerga need a lot more training than people thought,” Michael Knights, a specialist in Iraqi military and security affairs, told VICE. “Most of them have not had any combat experience in their lives. Whole generations of peshmerga have done nothing but sit on checkpoints and have done no operations at all, let alone this kind of counter-terrorist operation against a very effective force, which would even give the US a tough time.”

Who is the PKK?

The Kurdish Workers’ Party ­is a militant, far-left nationalist group who have fought for the self-determination of the stateless Kurd population since the late 1970s. The group was created by leader Abdullah Ocalan and a small group of radical students in 1978 with the objective of establishing a separate, autonomous state for ethnic Kurds in the south of Turkey.

Ocalan has been jailed since 1999 and last year declared a ceasefire with Turkey, renouncing the group’s goal of establishing a separate state within Turkish borders.

Better known by their Kurdish acronym, the PKK has more recently been fighting to protect the semi-autonomous Kurdish region in Iraq’s north from surging IS militants. With the Australian Defence Force arming the peshmerga fighters, experts believe that some weapons and munitions are likely to fall into PKK hands.

The relationship between the PKK and the peshmerga is historically frosty to outright hostile, but a shared enemy caused tensions to ease as Kurds unite against the jihadis. This is problematic for the Australian government, as the PKK is still regarded by Australia, the European Union and the US as an active terrorist organisation.

As Bernard Keane points out, in arming the PKK the Australian government could be breaching its own anti-terrorism laws.

What about the YPG?

The People’s Protection Units, or YPG, are the armed wing of the Kurdish Supreme Committee of Syrian Kurdistan, a de facto semi-autonomous state in northern Syria. The YPG have been fighting IS in Syria for the past two years and recently partnered with the peshmerga to defend a key Iraq-Syria border crossing.

The group has also fought alongside the PKK, working together in Sinja to protect Yazidis from ISIS militants. The YPG and PKK have reportedly even formed a special force, the Sinjar Defence Units, to defend the area.

The YPG recently claimed they had killed almost 700 IS fighters while protecting the Kurdish-held city of Kobane, in Syria’s north, and are quickly developing a reputation as the region’s best fighters. The YPG and the PKK are also linked through their affiliation to the Democratic Union Party, a Syrian Kurdish opposition party.

And PJAK?

The Party of Free Life of Kurdistan, also known as Free Life Party of Kurdistan, is a militant group seeking cultural and political rights for Kurds in Iran.

According to Australian National Security, PJAK is a close affiliate of the PKK and maintains training camps in northern Iraq. Iran has designated the group as a terrorist organisation.

How did Shiite militias get involved?

The Shiite-led Iranians have much to gain from stopping the Sunni-led IS in their tracks, even if it means teaming up with the US to do it.

Various militia groups, some of  them backed by Iran, are taking the fight to IS in Iraq with the force of US fighter jets behind them. Some of these groups were responsible for attacks against US soldiers and Sunni Iraqis during the Iraq War, and American analysts are cautious about getting too close to the (recent) enemy.

“Potentially what this could amount to is the US arming or advising Iranian proxies, some of which are on the terror list,” said Phillip Smyth, an expert on Shiite groups.

Retired US general David Petraeus, meanwhile, warned against the US becoming “the air force of Shia militias”.

Keeping a distance from these groups will be difficult considering the sudden alliance of the Iraqi army, militias, and the US air force is having success against IS on the battlefield. However, the militias are keen to present military victories as their own, not wanting to share credit with the US or the majority-Sunni Kurdish fighters who opposed the Shiite Iraqi government.

So, will weapons delivered into peshmerga hands end up in those of the PKK and other groups the West previously considered distasteful? It seems likely given the peshmerga, the YGA and the PKK are fighting side-by-side, but the real question is: will the West turn a blind eye?