Thousands of young Yemeni men have spent the past week advancing toward the centre of the capital Sana'a.

Many brandished assault rifles as they marched, while some wielded more traditional 'janbiya' daggers.

'Down with the government,' the men cried in unison. 'We need a new cabinet,' came the refrain.

The Houthis' enigmatic leader, Abdul Malik al-Houthi, has called on the government to reinstate fuel subsidies. With the deadline baring down upon him, the country's President Abd Rabbuh Mansur Hadi has shown no sign of bowing to demands, while the well-armed protesters continue to amass followers on their march into the capital.

This is a delicate moment for the country's transitional government, which looks increasingly fragile.

Who are the Houthis?

The Houthis have been around since the mid-90s but this is the first time that they have posed a mortal threat to Yemen's government.

Founded in the northern province of Sadaa, the Houthis emerged as a theological movement, associated with the Zaidi sect of Shia Islam.

The group transformed itself in 2004, arming itself and launching an insurgency against the government which they felt had discriminated against them.

Over the past decade, the Houthi movement expanded in military and financial power. It is in de-facto control of the Sadaa province.

However, since the country entered the period of the national political dialogue, the group has evolved its support base to encapsulate Yemenis from non-Zaidi and non-Houthi backgrounds.

As the group shifted its position and became more broadly anti-establishment, Yemenis from all backgrounds have found an affinity with the movement.

Danya Greenfield, acting director of the Atlantic Council's Hariri Centre, told IBTimes UK that the group's shift away from religion has helped broaden its support base.

"Its appeal is certainly broader than religious affiliation," she said, "in part because they are anti-establishment, and in part because of perceived nepotism and corruption [in the government].

"Their rallying cry is really drawing support among those who are frustrated and disgruntled with government performance in action.

"More than half of the country is below the poverty line, almost everyone is struggling to meet their very basic daily needs. Unfortunately the transitional government has been able to deliver very little in the way of improving day-to-day living standards in the post-2011 period," she said.

Government Failures

The current protests in Yemen have been focused on the government's cut to fuel subsidies.

They have drawn an increasing number of Yemenis on to the streets to voice their frustration over the cost of living for ordinary people and to condemn perceived corruption and nepotism in government.

The subsidies were withdrawn on 30 July, resulting in fuel prices almost doubling overnight as they reached a level on par with American gasoline.

While previous price hikes have sparked immediate street protests in Yemen, the response to the latest measures has swelled over August, resulting in the tense standoff in the capital.

The reason the fuel subsidies have provoked so much anger is partly because they were badly communicated to the Yemeni public, Greenfield told IBTimes UK.

This was an absolute disaster in terms of the way subsidy reform was rolled out. Despite lots of good planning and thoughtful communication plans that had been developed by external and international experts, the government was unwilling to put in place the kind of campaign that would be necessary to bring the public on board," she said.

"No connection was made publicly in a communications strategy that 'additional assistance is going to come to you, this is why we need to lift the subsidy' – it was an unmitigated disaster in terms of the way it was rolled out," she added.

Well Armed and Backed by Iran

Yemen has been awash with weapons for years. The Houthis are by no means the only non-government group that is armed and willing to fight for its political aims.

The coastal country is a haven for al-Qaeda in the Arabian Peninsula (AQAP,) a group that is primarily engaged in battles with Yemeni government security forces, while posing a threat to US interests in the region.

Moreover, many tribes across the country are also well-armed and readily use their weapons in inter-tribal fighting or to attack government forces they feel have overstepped the line.

The Houthis pose a major threat to the government because national security forces are engaged in multi-front battles elsewhere.

The movement "is well armed and well trained and they do essentially out match the government troops that have been dedicated to this fight," Greenfield told IBTimes UK.

A steady stream of funding and weapons from Iran is thought to be behind the Houthis' recent military successes, according to analysts.

Supporting the Houthis would be attractive for Tehran because it poses an additional threat next-door to its arch-rival Saudi Arabia. It is another front in the new cold war between the two biggest regional Muslim powers and has introduced a sectarian framework to Yemeni politics.

It is difficult to pinpoint when (and to what extent) Iran began supporting the group but a strict interpretation of Shia Islam is not at the roots of the Houthi movement.

However, it is possible that the movement could shift its goals to become more ideologically aligned with its financial backers should it ever assume political power in the country.

"This sort of Sunni-Shia split that you see in places like Iraq and elsewhere that has been indigenously an issue for decades does not exist in Yemen. This is a sort of fabricated, manufactured sectarianism that really emerges from this Iranian Saudi Cold War," Greenfield said.

What the Houthis Want

While the movement is outwardly rallying support among aggrieved Yemenis, their track record throughout Yemen's political transition offers some clues as to their next move.

In the wake of the massive street protests that toppled former President Saleh, the country entered into a national dialogue process that was followed by the introduction of a transitional government.

The former rag-tag militia was legitimised through their participation in the process and they made an effort to down arms for the duration. The group only embarked on military campaigns to seize territory when they felt they were being frozen out of the political process.

While their current campaign reflects their deep frustration with what they see as an inept and exclusive government, it also draws on general anger with the so-called political transition in the country.

But, for the Houthis to secure themselves a place at the table in Yemen's long-term political future, they will have to down their arms at some point.

The nature of the current crisis and the way in which it plays out could define the group's future as either an open political player, or a militant group operating in the shadows.