Saudi funding of Yemeni tribes for help against Al Qaida risks undermining central authority in the kingdom's poor neighbour at a moment when the government there needs all its clout to fight security threats.
The West relies heavily on Saudi Arabia to help stabilise Yemen: Saudi Arabia is the largest financial donor, bankrolling the government of ally President Ali Saleh Abdullah, helping supplying Yemeni forces and building hospitals.
But analysts and diplomats say Saudi Arabia is at the same time sidelining Sana'a by directly supporting tribes who dominate much of the country.
"Saudi support of the tribes has a clear negative impact on state-building and by extension, its ability to fight AQAP [Al Qaida in the Arabian Peninsula]," said Abdul Gani Al Iryani, a Yemeni political analyst in Sana'a. "The Saudis have refused flat out all Yemeni requests to desist from paying Yemeni tribes," he said.
Saudi counter-terrorism efforts are currently riding high. Last month, Saudi arrested 149 militants mainly linked to Yemen-based AQAP who had planned to stage attacks inside the kingdom and to send Saudis for training camps in Yemen and Somalia.
This was the latest success of Saudi intelligence after tipping off the US about a parcel bomb plot from Yemen, where AQAP has been both fighting the government as well as using remote areas as havens to plot attacks in the West.
Saudi Arabia has stepped up financial support for various Yemeni tribes in the past two years to improve its own security, diplomats and analysts say, due to worries about Shiite rebels in northern Yemen who briefly fought a border war with Riyadh.
While gaining some intelligence from tribal sources on the whereabouts of Al Qaida militants on their territory, the cash help has proved an obstacle to boosting Yemeni state authority — a vital ingredient in tackling economic problems, analysts say.
Another complication is that Islamic charities have long funded religious schools or mosques seen as recruiting grounds for Al Qaida.
"Saudi support on tribes is undermining government authority," said Barak Barfi, a former Visiting Fellow at the Brookings Doha Centre in Qatar. "Saudi Arabia does not want Yemen to be strong," he said.
A Western diplomat in Riyadh said some members of tribes on the Saudi payroll might also engage in cross-border smuggling which is undermining efforts to seal off the 1,500-kilometre joint border Riyadh fears Al Qaida militants use to infiltrate.