The sheikh's words boom from the speakers hanging from the mosque's stone minarets and carry through the dusty streets of Yemen's capital, Sana'a. "We must completely reject any international interference." The cleric, Abdul-Majid al-Zindani - an influential Yemeni whom the UN calls a terrorist - is one of more than 150 scholars and religious figures warning the west to stay out of Yemen, or face global jihad.
Outside the mosque's concrete walls, locals gather to hear Zindani speak. "I have a question," one man shouts. He wants to know if the US would invade Yemen. The people, he says, would fight back. "We are Yemeni people, all together - we will protect our country."
A new war has begun in Yemen, but it is still unclear who is fighting whom or how. Al-Qaeda in the Arabian Peninsula (Aqap) has thrown down the gauntlet and the Yemeni government has taken up the challenge. State-run media carry reports every day about air strikes that hit Aqap members in their hideouts near Yemen's border with Saudi Arabia.
Three days after the attempted attack on a Christmas Day flight bound for Detroit, Aqap released a statement boasting that the organisation had demonstrated its ability to design a "modern, advanced bomb" capable of "evading airport security" - in effect, a warning that it could attack anywhere in the world. The UK and the US had vowed to join the war from afar, but both countries have since toned down the rhetoric, as it has become clear that Yemenis do not support intervention. If the west moves in, "Everyone in the country will side with the terrorists," says Mohammad Saleh Risk, a school administrator living in Sana'a.
An insurgency in the north of the country, secessionist movements in the south, a national water crisis and widespread poverty, malnutrition and unemployment have created the conditions in Yemen for the rise of Aqap. According to Ali Saif Hassan, a Yemeni political analyst, Aqap has taken advantage of the chaos and people's suffering: "They come in through the cracks."
In northern Yemen, beyond the crumbling checkpoints staffed by skinny soldiers with old Kalashnikov rifles, jagged mountains separate a desert refugee camp from a battle zone. To the north of the grey peaks, the government has been waging a sporadic, six-year war against the Houthis, a Shia rebel group. To the south of them, the Mazrak camp houses more than 20,000 people in dirt-blown plastic tents. About 200,000 people have fled their homes since the war began.
Hussein Gaber says he first heard rebel gunfire in his village one night in August last year. He and his family fled when a bomb hit his neighbour's house. "We had no idea where to go," he says, leaning against a frayed mattress on the dirt floor of his tent. "Everyone loves his country and his village but we are better off here [in the camp] than being killed."
As victims of the northern war languish in camps, refugees stream into the south from the Horn of Africa, in particular Somalia, fleeing unrest and poverty. According to the government, there are about a million African refugees in Yemen. The UN says that as many as 75,000 arrived last year alone. They come by sea, late at night, often smuggled in on tiny fishing boats.
Hinda Ismael Mohammad fled to Yemen after her husband was killed by al-Shabab, an Islamist militia linked to al-Qaeda that is fighting for control of Somalia. "They slaughtered him," she says. Like Hinda, most Somalis come to Yemen in desperation, but there is concern among Yemeni government officials that al-Shabab, which intends to reinforce Aqap, will send in fighters disguised as refugees.
“The coastguard can't tell who are Yemeni fishermen, traffickers, refugees, smugglers or al-Qaeda," the deputy foreign minister Ali Muthana Hassan tells me. "It's the security problem of a porous border."
Hinda lives far from the fighting, in the Kharaz camp, 110 miles north of the port of Aden, with 14,000 other refugees. On the sandy road leading up to it, few travellers pass by and almost all those who do are on foot, carrying jerrycans or bottles. Water is scarce; for many families, this entails long hours of trudging up mountains or through deserts to collect enough to survive.
In Sana'a, residents fill plastic jugs at mosques or communal taps. Many believe the city will soon become the world's first capital to run out of groundwater. International organisations spend millions of dollars a year on Yemeni water management, but levels drop faster every year, according to Ramon Scoble, a water resources specialist for the German development company GTZ. The problem will get worse: the population, now 23 million, is expected to double before 2035. "What do you think people will live on?" he asks. Yemen's oil reserves are expected to run out by 2017 and the country is pinning its hopes on natural gas supplies.
As resources dwindle and poverty spreads, it is no surprise to many Yemenis that al-Qaeda appears to be growing stronger, especially among the young. Nearly half the population is under the age of 15; unemployment is approaching 40 per cent. Said to have more than 60 million guns, Yemen is also one of the most heavily armed countries on the planet.
Sitting in an internet café in Sana'a, Abuilah Ahmed, who is 18, says that life is a struggle for his generation. There is no work in the countryside, and militias on the roads set up barriers, kidnap, or demand cash for passage, making it hard to travel to the cities. He knows where the blame lies. "It's the government's fault," he says. "They don't give us jobs."