Invasive species are not generally considered bioweapons, but a few security experts, including some in the US military, are concerned about the damage they can cause to ecosystems and agriculture. For example, Lawrence Roberge, a professor at Labouré College in Boston, published a paper in Biosafety on the potential for adversaries to deliberately introduce non-native species as biological weapons. The Department of Defense is also concerned about invasive species because they can take over training grounds, erode natural resources, injure soldiers, and damage equipment. According to the US Defense Department’s Natural Resources Program, invasive species cause more than $138 billion in annual damage and management costs.

The irony is, we don’t need to wait for an intentional bioterror attack to feel the impact of invasive species. The United States already endures biological attacks from non-native species every year, which arrive in large numbers via the exotic pet trade.

Exotic pets are generally non-native wild animals, including rare or unusual ones, that are not typically domesticated. The definition is a moving target because many reptiles, rodents, and amphibians are becoming increasingly popular as pets. Invasive species—which can take the form of anything from microscopic organisms to plants, fish, and mammals—are those inhabiting a region where they are not native, and where they are causing harm. They displace native species by either eating them or eating their food. In part because they often have no natural predators in their new location, they can disrupt ecosystems, delicate webs of plants and animals that evolved to exist in balanced harmony. This can wreak havoc on environmental, animal, and human health. Beyond short-term health threats that a particular species may cause, the long-term threat to ecosystems and biodiversity poses a much larger risk. Some scientists argue that biodiversity loss in and of itself could be catastrophic for civilization, because of diminished ecosystem function in the form of reduced production of biomass, reduced decomposition of biomaterials, and reduced recycling of biologically essential nutrients.

Space invaders. Invasive species are brought to the United States—legally and illegally, intentionally and otherwise—by plane, ship, train, truck, and car. The exotic pet trade not only creates problems for domestic habitats, but by leaving a vacuum in habitats left behind, can also lead to the extinction of important species in the countries of origin. This is particularly problematic for wild bird populations that are being decimated in many countries by domestic and foreign demand.

One of the worst examples of an invasive species causing ruin to an ecosystem was the introduction of rabbits to Australia in the late 18th and early 19th centuries. Europeans brought domesticated and wild rabbits to the antipodes for food and hunting. By 1946, these rabbits’ progeny had invaded four million square kilometers (1.5 million square miles) of Australia, making them one of the fastest-colonizing mammals known, thriving in a wide range of habitats including forests, grasslands, and woodlands. Rabbits graze and burrow, causing serious soil erosion, reducing the survival of native plants, altering habitats, and attracting predators like foxes. They can strip a landscape bare, leaving nothing to eat for native animals or livestock. The imported rabbits have contributed to the decline or disappearance of numerous native species including the yellow-footed rock-wallaby, the malleefowl, and the southern and northern hairy-nosed wombats. Australian agriculture is estimated to lose more than $115 million Australian ($87 million US) per year because of rabbit overgrazing. Desperate to reduce rabbit populations, the Australian government resorted to biological agents such as rabbit calicivirus to kill them—infecting the animals with a deadly disease—but the animals eventually developed resistance.

In the United States, invasive species have been particularly devastating to Florida’s delicate ecosystems, where hundreds of invaders thrive. They include giant African land snails (which go by the scientific name Achatina fulica), among the “world’s 100 worst agricultural invaders” according to the Global Invasive Species Database. First imported as pets, they may also have arrived accidentally with cargo. According to the UN Food and Agriculture Organization the giant African land snail, which favors warm, tropical, humid climates and breeds quickly, consumes at least 500 different plants including common crops like peanuts, peas, cucumbers, and melons. While an ongoing cooperative program in Florida is working hard to eradicate them, these snails still have the potential to cause widespread devastation to the state’s natural resources. They also harbor rat lungworm, a type of parasite that can cause meningitis in humans. (Fortunately, in healthy individuals, the disease is usually self-limiting without medication.)

Burmese pythons, one of the largest snakes in the world and popular as pets, are another invasive species causing environmental, economic, and social concerns in Florida, especially in the Everglades. These animals eat native species of mammals, birds, and even an occasional dog, cat, or alligator, though they rarely attack humans unless provoked. Established populations were first reported in 2000, the result of breeding among animals that either escaped or were deliberately released into the wild. From 2006 to 2012, the US Fish and Wildlife Service spent more than $6 million dollars trying to eradicate them without success.

Lionfish, a species native to the Indo-Pacific region, were brought to the United States for home aquariums. Today, after being released into the wild and breeding, they’ve established themselves along the US East Coast and in the Bahamas, Bermuda, and the Caribbean. They are voracious predators and eat ecologically and commercially important species such as snappers and groupers. They’re aggressive and poisonous. Their venomous spines can sting unsuspecting divers and snorkelers and can cause intense pain, headaches, nausea, convulsions, and paralysis. One strategy people are using to reduce their numbers is to eat them—after the poisonous spines have been removed, of course. Some supermarkets are now selling their meat.

A global problem needs a global solution. Exact data on the extent of the exotic animal trade is not available, but according to the US Fish and Wildlife Service, the illegal wildlife trade alone—which includes the unlawful trade of live animals as well as parts and products derived from them—is worth billions of dollars. The Humane Society of the United States estimates the illegal global trade in wild animals is worth $10 billion or more per year.

Concern about the illegal wildlife trade goes back to 1900 with the passage of the Lacey Act, the first federal law protecting wildlife by prohibiting the interstate or foreign trade of any fish, animal, or plant taken in violation of US law. Today, criminal penalties for individuals who illegally import or export fish, wildlife, or plants include fines of $20,000 or less, imprisonment for five years or less, or both. Unfortunately, these penalties, which are insignificant for individuals involved in multibillion-dollar industries, do little to deter the perpetrators.

The legal importation of animals poses enormous challenges too. From 2005 to 2008, the United States legally imported more than one billion live animals, according to a 2010 report from the US Government Accountability Office. Regulatory authority over live animal importation is spread across four US federal agencies: the Department of Agriculture’s Animal and Plant Health Inspection Service, the Department of the Interior’s Fish and Wildlife Service, the Department of Health and Human Services’ Centers for Disease Control and Prevention (CDC), and the Department of Homeland Security’s Customs and Border Protection. The CDC regulates the importation of pet dogs, cats, African rodents, civet cats, monkeys, and turtles, among other animals, but most are neither quarantined nor tested for infectious diseases.

State-level rules exist too. According to Born Free USA, a nonprofit animal advocacy organization, approximately 22 states regulate exotic animals as pets. This number, though, suggests a poorly coordinated, patchwork response that does little to protect the country as a whole against invasive species.

The trade in exotic animals is a global issue that requires a global solution. In 1973, representatives from 80 countries met under the auspices of the World Conservation Union and agreed on a resolution to ensure that international trade in animals did not lead to the extinction of any species being traded. The resolution enshrined the endangered species list. In response, the United States passed the Endangered Species Act of 1973, prohibiting the unauthorized taking, possession, sale, or transport of endangered species. The new law gave equal authority to the Departments of Agriculture and the Interior for enforcing restrictions on the import and export of listed plants, but unfortunately, did not explicitly mention the exotic pet trade.

There are efforts in place to reduce wildlife trafficking. Officers from the US Fish and Wildlife Service inspect declared shipments of businesses involved in the animal trade. Since 2014, it has stationed agents at US embassies overseas to increase international cooperation, including in Thailand, Tanzania, Botswana, and Peru. In July 2013, US President Barack Obama issued an executive order on combating wildlife trafficking, aimed at working with partner countries to reduce demand for illegally traded wildlife while allowing legal and legitimate commerce. The order does not, though, explicitly call for enhancing regulations and surveillance of the exotic pet trade.

In short, it appears that exotic pets fall through the regulatory cracks much to the peril of our nation’s ecosystems and agriculture. In fact, they should be considered potential biological threats, and the regulation loopholes allowing their unfettered importation should be closed.