The extraordinary events unfolding in Egypt, and the toppling of Tunisia's government before it, have led to a wave of predictions about popular uprisings in the Arab world. Many assume regime change is the inevitable conclusion and, on its face, Yemen would seem to be most vulnerable.
Last week's "day of rage" saw thousands of Yemenis take to the streets in peaceful demonstrations, demanding economic, environmental and political reforms. Organisers pledged to continue every Thursday until President Ali Abdullah Saleh, leader of North Yemen from 1978-1990 and a unified Yemen since its creation in 1990, agrees to carry out certain key reforms.
The recent unrest, however, does not mean that Sana'a's Tahrir Square will soon mirror the revolution unfolding in Cairo. While analysts may point to a singular wave of democratic revolutions rippling across the region, Yemen is not Tunisia or Egypt. In fact, Yemen's protest movement is unlikely to instigate regime change, for four reasons.
First, this movement is not grassroots or representative. Instead, it is organised and led by the Joint Meetings Party (JMP), Yemen's main opposition coalition that includes the Islamist reform party, Islah, the former ruling party of South Yemen, and several smaller parties. Although some protesters have demanded that Mr Saleh step down immediately, the JMP has characterised its objectives as reform. This is not surprising since Islah, the JMP's largest party, constitutes an entrenched player in Yemen's political patronage system. Many of its members remain allies of the regime, and the party has joined coalitions with the ruling General People's Congress (GPC) in the past.
The evolution of the protest movement - specifically, its leadership's ability or willingness to build a broader grassroots movement representing Yemen's vast political, ideological and, perhaps most importantly, geographic diversity - will determine the scale of future demonstrations, as well as their impact. Although many Yemenis think the JMP can unite shared grievances, it lacks credibility in some influential circles. Consequently, if the protest movement reflects the agenda and political interests of the JMP, traction will remain slow and limited.
Second, Mr Saleh appears to be learning from the mistakes of his fellow Arab leaders. The former Tunisian president Zine El Abidine Ben Ali was always a few days behind citizens' demands, a trend the Egyptian president Hosni Mubarak seems to be following. By contrast, the more politically astute Mr Saleh pre-empted last week's day of rage demonstrations by offering a number of eleventh-hour economic and political concessions: slashing income taxes, reducing students' tuition and raising civil servant and military salaries in an obvious ploy to ensure their loyalty.
Most significantly, he pledged to step down in 2013, not to pass the presidency to his son, and to delay April's parliamentary elections in order to remedy fraudulent voter records and allow opposition parties to organise. His pledges did not dissuade tens of thousands from marching against the regime, but so far, protests have been largely peaceful and cautious.
Third, Mr Saleh's relationship to the Yemeni people is more ambiguous than the ties that bind other regional leaders to their masses. In contrast with Egypt, Yemen has a recent history of electoral democracy and freedom of speech and assembly, although these rights have deteriorated in recent years. Furthermore, Yemen's quagmire of tribal interests places limits on the central state. Successive governments, including Mr Saleh's, have generally attempted to placate the country's strong and autonomous tribes - not to mention political parties and movements - through patronage and manipulation rather than physical domination.
As a result, Mr Saleh's rule is more akin to a human hand than an iron fist: occasionally opening to bestow gifts, sometimes closing and coming down with force, but more often than not snatching up money and resources for itself. This complexity, combined with the awareness that Yemen's numerous crises have placed it on the brink, gives Mr Saleh some leeway with the Yemeni population.
Finally, Yemen already faces three acute political crises that would severely complicate any transition: the Houthi conflict in the north, the secessionist Southern Movement and the rise of al Qa'eda in the Arabian Peninsula. While these groups share core grievances with all Yemenis, the regime, if not most Yemenis, considers them enemies of the state.
In fact, Mr Saleh has frequently used these issues to justify wider repressive measures, and it is possible that he may now try to conflate them with the protest movement. Bringing the Houthis and the Southern Movement into national negotiations would be essential, but it is unclear which of the three groups would join any Yemeni state in its current northern-dominated, republican form.
The point is that unlike Egypt's opposition - politically, socially and regionally united in calling for Mr Mubarak's departure - Yemen is far more stratified. With these more torturous political dynamics, a popular revolution may not be viable.
What is possible in Yemen is a more intentional process of structural reform and democratic transformation. While the ongoing protests in Sana'a, Aden, Ta'izz and elsewhere may not be as explosive as those in Cairo, the Yemeni people now expect their president to enact real reforms. If they can continue to pressure Mr Saleh and his circle of elites internally, with the international community applying accountability externally, there is a chance - however unlikely - to achieve an accelerated change peacefully and without the kind of tumult, violence and disruption we have witnessed elsewhere.
James R King is an independent analyst specialising in Zaydism, Yemen and the Middle East