Cocaine availability in the United States has decreased in recent years, while the availability of heroin and methamphetamine have soared in certain regions of the country, a new study by the Drug Enforcement Administration (DEA) found.

The National Drug Threat Assessment Summary, which compiled illegal drug trends through 2012, found that infighting between Mexican cartels, declining coca production in Colombia and ramped-up drug-interdiction efforts in the U.S. have all contributed to the decline in the availability of cocaine. In 2011 approximately 37,200 pounds of cocaine were seized along the U.S. border with Mexico while in 2012 only about 15,700 pounds were seized, according to the National Security Service statistics.

“This is a very important shift because cocaine has traditionally been the main driver of profits for transnational organized crime groups,”Andrew Selee, vice president for programs at the Woodrow Wilson Center in Washington D.C, told Fox News Latino. The RAND Corporation estimates that U.S. retail spending on cocaine alone is around $30 billion a year annually.

DEA officials also cited the move by cartels into markets overseas as a key reason for the decline in availability of cocaine in the U.S. Cartels from both Mexico and Colombia are working with traffickers and terrorist organizations in Africa, using the region as a transshipment zone for booming drug markets in Europe.

The DEA announced last year that there are links between Mexican cartels and criminal groups in Mozambique, the Democratic Republic of the Congo, Ghana and Nigeria. The Sinaloa Cartel, for instance, is known to have ties not only in Europe but throughout Latin America, Africa, Asia and Australia, where a booming trade has developed.

“Now that these terrorist groups have lost their state sponsors they need a way to fund their operations and trafficking drugs to Europe is a very lucrative business,” said Rusty Payne, a spokesperson for the DEA. “Europe has about as strong a demand for cocaine as anywhere else in the world right now.”

U.S. law enforcement officials are facing what Payne says are epidemic levels in the use of heroin and other opiates such as Oxycontin in Midwestern cities and on the Eastern seaboard. Prescription opiates are relatively expensive, so cheaper forms of heroin – such as Mexico’s black tar and Colombian white – have made inroads among middle class drug users.

A National Survey on Drug Use and Health study showed that the number of new heroin users nearly doubled from 91,000 in 2002 to 178,000 in 2011.

“We’re dealing with a heroin epidemic and prescription pill epidemic,” Payne added. “These two are definitely correlated.”

Officials in the Southwest and on the West Coast, on the other hand, have to contend with the growing importation of methamphetamine from so-called “superlabs” in Mexico.

The National Drug Threat Assessment Summary states that seizures of Mexican meth coming across the border have increased along with the quality of the drug – between 2007 and 2012 the purity went up almost 130 percent while its cost plummeted more than 70 percent.

“Methamphetamine is an attractive drug to the cartels because it’s easier to smuggle, make, and its profits margins are huge,” said George W. Grayson, a comparative politics professor at the College of William and Mary. Grayson added that the Sinaloa Cartel has become the leader in meth thanks to sophisticated, well-funded facilities that produce some of the most addictive versions of the drug.

While the DEA’s assessment paints a picture of a drug market in flux, it's unlikely to alter the landscape too dramatically.

“Mexican cartels move all of these drugs, so the changing trends won't reduce their overall involvement,” Shannon O’Neil, a senior fellow at the Council of Foreign Relations, told Fox News Latino via email. “Cocaine is their most profitable illegal drug product (they have other illegal lines of business as well), so this shift will hit the bottom line somewhat.”

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