PUERTO CHIAPAS — In the small Mexican fishing harbor of Puerto Chiapas, near the border with Guatemala, drug trafficking boats aren't that uncommon a sight. At first glance, they look like like regular fishing boats. What sets them apart are the state-of-the-art motors.

Chiapas state is one of the most peaceful in Mexico, and Puerto Chiapas, a modest village of 8,000 inhabitants, is no exception. And yet, as a midway point between the region where drugs are produced, South America, and the place they're consumed, the United States, the small harbor occupies a strategic position in the world of transnational narcotics trafficking. Indeed, some 80% of the trafficking is said to travel off this part of the coast.

Little wonder that locals sometime stumble upon the occasional surprise. "Let's say I'm a fisherman and I find a few kilos of cocaine while I'm fishing," says a local sailor, breaking into a gap-toothed grin. "Of course I'll take it. It's an opportunity, right?"

All that trafficking has also made the waters off Puerto Chiapas, in the eastern Pacific Ocean, one of the main fronts in the war on drugs, which former U.S. president Richard Nixon launched in the 1970s. Last year, the U.S. Coast Guard seized more than 200 tons of cocaine. The Mexican Navy, which also contributes to the effort and has become a key ally of the U.S., seized more than 23 tons, five times more than it did in 2015.

For James Passarelli, a U.S. Coast Guard captain, Mexico is at the epicenter of the battle. "The Mexican Navy has made considerable efforts in recent years to increase its participation in drug operations, to modernize, expand its fleet and increase joint exercises at sea," he says.

But the cooperation between the United States and Mexico has also had its share of setbacks. In 2011, a senior member of the Mexican police force leaked information that had been given to him by the U.S. Drug Enforcement Administration (DEA), an investigation by the site ProPublica revealed. Upon learning about the existence of an informant, the Los Zetas cartel executed dozens — hundreds perhaps — of people in the small town of Allende.

Since then, the United States has opted for a rapprochement with the Mexican navy, which it considers to be more open, reactive, and, above all, more reliable than the police. "The relationships are good ... The interest is mutual," a senior Mexican naval officer says. "They don't want the drugs coming into their country, same as us. This forced us to get a lot closer."

Uncomfortable allies

The United States has a lot to gain from this relationship. In October, U.S. President Donald Trump declared opiate use — which caused nearly 60,000 deaths in the country in 2016 — a national "public health emergency." But at the same time, Trump's uncompromising stance in ongoing negotiations around NAFTA — the free trade agreement linking the United States, Mexico and Canada — could compromise matters.

"We've come far on this issue but things seem to have come somewhat to a standstill," people on the Mexican side say. Several ministers have warned that if the United States withdraws from the treaty, Mexico will review its cooperation on security and immigration.

The Americans say they intervene in only 20%-30% of cases.

A recent DEA report suggests that cocaine production as at an all-time high, with Colombians trying to sell as much of the drug as possible before the peace process between the government and the FARC complicates things. The area of coca plantations in the country doubled between 2013 and 2015, reaching 188,000 hectares last year, resulting in a 41% increase in production.

Keeping track of those drugs as they make their way north, through an area of ocean water that is roughly the size of the United States (nearly 10 million square kilometers) is a Herculean task. And limited budgets mean that not all of the information obtained translates into action. Even when they're aware of movement, the Americans say they intervene in only 20%-30% of cases.

"Our goal in the United States is to strengthen our partnerships so that Mexicans can conduct their own operations," Captain Passarelli says.

Speed and stealth

To avoid being detected, traffickers use several methods and different types of vessels. First off are the pangas: fast boats made of wood and fiberglass. They tend to be about 10 meters long, and can carry between 500 and 1,200 kilos of cocaine. They're the most common because they're cheap to build and are often used as fishing boats in the region.

After that there are the so-called "low profile" boats, of which only a tiny part can be seen on the surface of the water. Some are long and slender enough to pass through the waves; others rely on speed, with three engines instead of one or two. Most are painted in blue, to better blend with the water, and can retain the exhaust smoke, so as to avoid the increased vigilance of air patrols.

There are fears on both sides of the border that it will curb Mexico's enthusiasm for cooperation.

Finally, there are submarines or semi-submersible vessels that sail just below the water surface and can carry up to seven tons of cocaine. "These are more complex and cost several million dollars to build, but in one journey, they can yield more than 200 times the investment," says Passarelli, who has served in the U.S. Coast Guard for more than 25 years. "The cartels are constantly experimenting, trying out new techniques, new ways of doing things," he adds.

According to U.S. and Mexican authorities, recent technologies allow organized crime to venture further and further into the high seas, sometimes as far away as 1,600 kilometers offshore.

Will the Trump presidency mean the end of this valuable collaboration? At the very least, there are fears on both sides of the border that it will curb Mexico"s enthusiasm for cooperation. As one veteran from the Mexican Navy explains: "These negotiations around NAFTA could certainly impact our relationship, making our troops less inclined to take part in exercises and share information."