Border buffer zone aside, it can be hard, in some ways, to figure out where the Saudi state ends and the Yemeni state begins. Ordinary Yemenis, for example, still make the journey north to the Saudi Red Sea city of Jeddah to attend the majalis, or councils, of King Abdullah. There the Yemenis petition the Saudi monarch for favors and cash handouts, with the blessings of Yemeni President Ali Abdullah Saleh. "Go try your luck," Saleh, ever pragmatic, is quoted as once telling his people on their cross-border begging missions.
In many ways, Saleh and Saudi Arabia allowed the Yemeni state and its elites to go on the Saudi dole as well. Since the 1980s at least, wealthy Saudi Arabia, with its habit of dispensing largesse to soothe troubles and cement loyalties, has routinely dispensed up to several billion dollars annually to thousands of Yemeni tribal leaders, security officials, and other Yemeni elites, as well as to Yemen's government. But by all accounts, the flow of Saudi patronage has narrowed to far fewer tribal leaders amid Yemen's present upheaval.
These days, in a further blurring of frontiers, Saleh presides not from his outwardly nondescript walled compound in the Yemeni capital of Sanaa, but from a hospital bed in the Saudi capital of Riyadh. Saleh, medicated for pain, is recovering from a June 3 assassination attempt. Aides acting in his name issue birthday greetings to fellow world leaders to try to show the Yemeni president still feebly in charge. After five months of state collapse in Yemen and his own near death, however, the president is no longer politically capable of wielding power, but remains temperamentally incapable of yielding it. Saudis urge Saleh to quit while he still has "honor, rather than leave with danger and harassment," said Prince Turki bin Mohammed bin Saud al-Kabeer, the Foreign Ministry's undersecretary for multilateral relations, but the badly burned Yemeni leader still refuses to sign a Saudi-backed deal for his resignation.
Saudi Arabia learned the lesson again in a 2009 military operation against Yemeni Shiite Houthi rebels, in which friendly fire is said to have claimed some Saudi troops. With Yemen now showing itself increasingly unable or unwilling to control al Qaeda in the Arabian Peninsula and other extremists forces, Saudi Arabia is stepping up its preparation of special forces able to operate across the border in Yemen's rough terrain, according to analyst Nawaf Obaid and other Saudis.
Saudi Arabia's strategic direction on Yemen has been in flux, and not just because Saleh's government has imploded. Part of it is due to changing power dynamics within the monarchy: Saudi Crown Prince Sultan, who long dispensed the patronage payments to Yemen through the kingdom's special committee for Yemen affairs, has been ill for years and is reported to be under medical care in New York. Prince Nayef, already much involved in Yemeni affairs as interior minister and as the father of Saudi Arabia's counterterrorism chief, Prince Mohammed bin Nayef, has assumed much more control of the Yemen portfolio, according to many longtime observers. Prince Nayef is regarded as heavily focused on security, which means Saudi Arabia, like the United States, may be seeing Yemen ever more narrowly through a counterterrorism prism. With Prince Sultan in poor health, Prince Nayef is now seen as King Abdullah's most likely successor.
Prince Turki, the foreign affairs undersecretary, confirmed to me that Saudi payments through Prince Sultan's old Yemen committee were suspended this spring.
Saudi payments, however, have since resumed to some Yemeni tribal leaders, Hamidaddin said. Jamal Khashoggi, a political analyst close to the royal family, told me that Yemenis still getting Saudi financial support include the powerful al-Ahmar family, which leads the Hashid tribal confederation in Yemen. The al-Ahmars have been principals in fighting the Shiite Houthi rebels in northern Yemen, in supporting dissent against Saleh, and in fighting loyalist Saleh forces in Yemen's capital.
Saudis variously describe the payments to Yemenis as both an effort to secure stewards of Saudi Arabia's interests in Yemen and an effort to channel aid to Yemen, by far the poorest country on the Arabian Peninsula, in a way that can't be skimmed off by Saleh's notoriously corrupt regime.
The stipends "are a way to help them, Yemenis at large and the central government," Prince Turki told me. "We're not bribing them. Bribes don't bring you stability."
Saudi leaders fear massive refugee flows and even greater trafficking of arms and extremists into the peninsula if Yemen keeps collapsing. In Yemen, "a strong government is essential for us," the prince said.
"Let's call them friends of Saudi Arabia," Khashoggi said of those receiving patronage. "Saudi Arabia pays them money handsomely for various services such as influence, protection, stability. That's what matters in Saudi Arabia."
In fact, said Barbara Bodine, former U.S. ambassador to Yemen, "the Saudis have really gotten very little for their money, but have a dilemma in that they can't cut it off entirely. Yemen needs the money, and without it, it would probably implode."
Saleh himself likewise governed through his own patronage system, divvying out Yemen's wealth and influence to elites to keep them on his side and blocking development of state institutions in the process.
The lack of focus on government-building, including the failure to build a functioning tax system, means that whoever succeeds Saleh "is going to need Saudi 110 percent," said Fernando Carvajal, an expert on Saudi-Yemeni relations at Britain's University of Exeter. Yemen will need Saudi Arabia's money "for restructuring and to pay a new patronage network."
As a result, rival candidates for power seem to be pitching a line that they think will hook the conservative Saudis -- with members of the official coalition of opposition parties telling reporters that democracy is an adventure that Yemen's not quite ready for, Carvajal noted.
Saudi Arabia, other Gulf countries, and countries around the world that have pledged aid to Yemen say they will open the taps for development and aid in Yemen after the GCC deal clears.
For now, though, all wait for Saleh to quit, if he ever does. From his hospital bed, Saleh promised King Abdullah in a phone call last month that he would sign the GCC deal, according to Prince Turki. (Saleh has reneged on the same promise to others at least three times. The Yemen leader will try to go back to Yemen, one official predicted, if he has to roll himself there "in a wheelchair.")
If Saleh signs, Saleh's son and nephews, who have refused to yield up the presidential palace or their loyalist forces in Saleh's absence, will be no problem, Prince Turki predicted. He made a shooing gesture: "Boys, go on."
Beyond that, the al-Saud family has no desire to immerse itself in Yemen, the prince maintained. He cited the second cautionary tale on Yemen from the late King Abdul Aziz: In the 1930s, the king's sons Saud and Faisal entered Yemen in a dispute with the then-ruling Yemeni imams. Faisal, in his youthful enthusiasm, raced with his troops far down the Yemeni coast and urged his father to take advantage of his military advance.
No, pull back to the border, King Abdul Aziz is supposed to have directed his headstrong son. "That is Yemen. You don't stay in Yemen."
For Yemenis, suffering under worsening shortages of food, water, gasoline, and electricity in a country adrift, the answer to the question of what comes next in the stalemate lies partly with Saleh, partly with themselves, and partly with Saudi Arabia.
Critics for decades have accused Saudi Arabia of purposefully fostering a Yemeni government too immature to ever pose a state threat to Saudis. "Keep Yemen weak," King Abdul Aziz is supposed to have told his sons on his deathbed, in one of two such warnings the founder of the modern Saudi state handed down to his sons and grandsons.
In interviews, Saudi officials and their supporters insist that even if Saudi Arabia once favored a Yemen that was neither too stable nor unstable, its position has changed: Saudi Arabia now wants a Yemeni government strong enough to quell the country's internal chaos.
"Saudis more than anyone else don't like chaos. Change they can deal with; they don't like chaos.... For the Saudis, Yemen is a problem to manage. It's not a problem to be fixed," said a Western diplomat.
The kingdom's supporters maintain that Saudi Arabia deserves credit for pushing a Gulf Cooperation Council (GCC) plan that would force out Saleh -- a longtime Saudi ally, though an unreliable one -- and bring new elections in Yemen.
But can Saudi Arabia, among the most risk-adverse of states, tolerate the kind of unruly transition to democracy that demonstrators in Yemen's streets have been demanding for the past five months?
Even in Saudi Arabia, many doubt it.
"The government has always used this money to control people, silence them. It worked for a long time," Mazin Mutabagani, a scholar and Yemen expert at the King Faisal Center for Research and Islamic Studies, told me. "If they could give Ali Abdullah Saleh a new life, they would give [it to] him, to go back. They are fond of dictators."
Under Saleh, whose rise to the presidency in 1978 was supported by Riyadh, Saudi Arabia has denied Yemen the monopoly of power and integrity of borders that are the basics of statehood, through payments that blur the allegiances of Yemeni tribes and others, and through cross-border security operations, argues Abdullah Hamidaddin, a political analyst in Jeddah.
"Increasing the autonomy of the tribe always degrades the authority of the central government," Hamidaddin told me, adding, "In what other countries do citizens receive a salary from a foreign government?"
As a result, in Yemen "the state is never seen as a state. It's seen as another tribe, and one that is competing with other tribes for resources," Hamidaddin says. "This is the devastating concept that has happened to Yemen in the last 20 years."
Hamidaddin, at 42, approaches the Yemen question from a different background from most. He is the grandson of the last in a line of imams that ruled north Yemen off and on for 1,100 years, until a republican military regime that preceded Saleh's overthrew the Yemeni imamate in 1962.
The eight-year republican-royalist war that followed between Hamidaddin's uncles and the republican Yemeni military commanders show how hard a slog warfare is in Yemen's mountains and caves, and how unpredictable its outcome. Egyptian President Gamal Abdel Nasser's Arab nationalist regime intervened on behalf of Yemen's republican coup leaders, thinking that they could defeat the Yemeni royalists in a few weeks with a battalion of Egyptian special forces and some aircraft. But in a Cold War dog pile of strange alliances, the United States, the Saudi and Jordanian monarchies, the Shah of Iran, and by many accounts even Israel gave financing, training, and arms to the Yemeni royalists and Yemeni tribes against the Egypt- and Soviet-backed Yemeni officers. The royalists lost -- after nearly a decade of fighting that killed more than 20,000 Egyptian troops. Arab regimes emerged shaken by the difficulty of fighting in rugged Yemen.