When you think of Gibraltar—and who doesn’t once in a while—you may think of its rare breed of wild monkeys, the Barbary macaques, that roam freely over the rock that constitutes the bulk of the peninsula’s terrain. Or your thoughts may turn to John Lennon and Yoko Ono who famously married there in 1969. Or perhaps you envision red-faced tourists, drinking Guinness, at one of the many pubs on the tiny sliver of land that has been under United Kingdom jurisdiction since 1713.

If you’re a British politician, though, the rocky promontory on the Spanish coast inspires nothing so much as a headache these days.

Recently, the British Overseas Territory of Gibraltar has become a major point of contention as Spain has sought to test the British sovereignty over the peninsula by imposing harsher border checks that have resulted in long lines. The Spanish Foreign Minister, Jose Manuel Garcia-Margallo, also threatened to impose flight restrictions and charge motorists the equivalent of $67 for crossing the border in addition to investigating the tax status of the 6,000 people who live on the peninsula but own properties on the Spanish mainland. “The party is over,” Garcia-Margallo said.

The tension, brewing for more than 300 years, erupted last month when Gibraltarians dropped more than 70 concrete blocks into waters near the Spanish border in what they say was a necessary move to create an artificial reef to replenish depleted fish populations. However, the Spanish government says the cement blocks impaired Spanish fishermen from trolling the same waters for shellfish.

Garcia-Margallo responded by increasing border controls between the two nations, and, since then, the usual crossing, which generally takes just under an hour, now can take as much as eight hours to pass, leaving tourists stranded in stifling heat and workers missing their jobs. Some 10,000 people cross the border every day.

“This is much more than a traffic jam at the border,” Dominique Searle, editor of the Gibraltar Chronicle told The Daily Beast. “The risk is beyond inconvenience. If they start blocking food and supplies, then we’re in real trouble.”

British Prime Minister David Cameron has said he is “seriously concerned” about Spain’s move, and Gibraltar’s own prime minister, Fabian Picardo, has called it the “politics of madness. “This is saber-rattling à la North Korea,” he said in a television interview. Picardo also called upon the British Royal Navy to send warships to help protect the area. “With more naval assents, it would be easier to show that these are British waters,” Picardo told a British newspaper.

Spain has insisted that the only way it will soften its stance is if the Gibraltarians move the artificial reef to allow Spanish fishermen to troll the area. “Hell will freeze over before Gibraltar removes the concrete,” Picardo insisted. But Searle and other native Gibraltarians say the move to build the reef was about much more than the fishing population. “Putting up the reef was a provocation,” Searle told The Daily Beast. “If the waters were Spanish, they would stop the fishing, too, but this is about politics, not fishing. No matter what the issue, though, being cut off by land, sea, and air is worrying to Gibraltarians.”

The threat of closed airspace and a hefty border fee would change life for the tiny nation, which has a population of 30,000, and Picardo says that he won’t allow that to happen. “Things will get worse before it get better,” he told a group of Gibraltarians at a weekend rally. He is gathering a dossier outlining all of the threats to Gibraltar’s sovereignty in the last several years, including an incident in June when a Gibraltarian jet skier was fired upon by a Spanish Guardia Civil vessel, caught in a dramatic video. He is also collecting testimony from people as they make it across the border. “We’re hearing complaints of inhumane treatment by border guards, which is in direct defiance of EU law.”

Some of the border inspections have been intrusive, including body searches, and the emptying of full cars and campers by Spanish authorities. The Spaniards have defended such actions by insisting they are looking for those who might be smuggling goods such as cigarettes or drugs, or even large sums of money to the rock, which is known as a tax haven thanks to its low income tax. In recent years, a slew of online gambling companies have relocated from the United Kingdom to Gibraltar to enjoy the lower taxes.

The U.K. is urging the EU to send officials to conduct checks on the border crossings to ensure that all is being carried out in accordance with European Union law. Because the United Kingdom is not part of the open-border Schengen Agreement, anyone moving between Gibraltar and Spain must go through passport control. “We acknowledge Spain’s right to protect and police its own borders. However, the searches and other delays now happening at the Gibraltar crossing are nothing to do with crime or immigration and everything to do with causing inconvenience to Gibraltarians,” said Ashley Fox, a British member of the European Parliament, in a letter urging the European Union to intervene. “They have no legitimate purpose.”

So far, the tension doesn’t show any sign of abating—indeed, some say Spain is using the Gibraltar issue to divert attention from its own problems. “Gibraltar has been a convenient whipping boy for Spain for decades,” deputy chief minister of Gibraltar, Dr. Joseph Garcia said during an interview with Cyprus radio station. “Whenever they have serious economic or other difficulties at home, they simply show the Gibraltar card, and start saying Gibraltar is Spanish.”

For now, the thousands of tourists and workers, who need to cross the border, are caught between a rock and a hard place.