The deployment of the Saudi army along the Yemeni border has significantly impeded the cross-border smuggling of qat, a plant used widely as a stimulant, causing its price to triple and dealing a significant blow to the local economy.
A local smuggler told the London-based A-Sharq Al-Awsat that the same quantity of qat that was previously sold in Saudi Arabia for 100 rials was now going for 300 rials because of the added danger smugglers were facing.
Production and smuggling of qat is one of the main sources of income for many families in northern Yemen, including rebels who use the revenue to finance terror activities.
The drug is consumed extensively by the local population, many of whom chew on it for several hours a day.
The plant is illegal in neighboring Saudi Arabia but is regularly smuggled into the kingdom through Yemen's northern border, where Al-Houthi rebels are based.
"The best qat comes from the northern regions of Yemen and part of it is smuggled illegally into Saudi Arabia," a Yemen expert told The Media Line on condition of anonymity. "But everyone knows it's going in, and some of the Saudi royal princes probably benefit from it."
While it is likely the Al-Houthi rebels have benefited financially from qat smuggling, the expert said it was probably not their sole source of income; otherwise the Yemeni government would have eradicated qat farms long ago.
The expert said that even if more soldiers were deployed along the border, it was impossible to monitor the entire boundary all the time.
"They will never control all of it because it's a very rough terrain and the Al-Houthis will try to shoot them," he said. "The economy of the war is a very complex one and I'm not entirely sure the financial issue is that important. If you consider ammunition, they can get it by stealing from the army, and that's what they've been doing. There are people inside the army who let the Al-Houthis get the weapons."
Saudi military operations are said to have hampered qat smuggling across the border by more than 50%, according to data provided by the Yemeni border patrol forces to A-Sharq Al-Awsat.
Whereas the average yield of border control seizures is usually between 62 and 67 tons of qat a week, forces seized only 28 tons of the substance during the first week of the Saudi offensive, which began earlier this month.
A security source in Jazan, one of the conflict areas in Saudi Arabia bordering Yemen, confirmed these figures and said the reason for the plunge in smuggled qat was the extensive deployment of Saudi soldiers along the border in the areas most prone to smuggling of illegal substances.
Al-Houthi fighters belong to the Zaidi minority, an offshoot of Shia Islam. The Zaidis are a minority in Yemen but are the majority in the country's north. Al-Houthi fighters wish to restore the Zaidi imamate, which was overthrown in a 1962 coup, and accuse the Yemenite government of being too closely allied with the United States.
Rebels have been engaged in a protracted conflict with the Yemeni army since 2004.
The latest round of fighting follows a government-launched offensive earlier in August, codenamed Scorched Earth.
Numerous rebels fleeing north across the border prompted a massive Saudi air and ground offensive, in an attempt to drive the Al-Houthis back into Yemen.