Illegal wildlife is one of the world’s largest contraband trades, netting an estimated $19 billion a year, not including illegal fisheries and timber. While all Southeast Asian countries and many others outside of the region are involved, Vietnam plays a paramount role. The country is a major thoroughfare for wildlife goods bound for China, which arrive overland from Cambodia, Thailand and Laos; by ship from Malaysia and Indonesia; or by air from Africa.

“After China, Vietnam is the next port of call in terms of where to look to figure out what’s going on with wildlife trade,” said Dan Challender, a co-chairman of the pangolin specialist group at the International Union for Conservation of Nature.

Vietnam is also a significant consumer of wildlife, especially those yielding the ingredients for traditional medicine, such as rhino horn, which is used to treat everything from cancer to hangovers. The exotic meats of rare animals are seen as luxuries by a rising middle class eager to advertise its prosperity.

“Pangolin is frequently the most expensive item on the menu, so ordering it is an obvious way to show off to friends and colleagues,” Dr. Challender said. “The fact that it’s illegal isn’t played down and is even attractive, because it adds this element that you live beyond the law.”

International concern about the trade has never been greater, but conferences, new enforcement strategies and ivory crushes have yet to make a dent.

In February, the Obama administration issued a plan to curb illegal wildlife trade by strengthening enforcement, reducing demand and sending a handful of agents abroad. The United States is the second-largest market for illegal wildlife products, but only an estimated 10 percent of traffickers are caught because of inadequate resources supporting enforcement, as well as legal loopholes pertaining to certain products, such as ivory.