GUADALAJARA, Mexico (AP) — Mexican troops have made a historic seizure of 15 tons of pure methamphetamine in the western state of Jalisco, an amount equivalent to half of all meth seizures worldwide in 2009.

The sheer scale of the bust announced late Wednesday in the western state of Jalisco drew expressions of amazement from meth experts. The haul could have supplied 13 million doses worth over $4 billion on U.S. streets.

“This could potentially put a huge dent in the supply chain in the U.S,” said U.S. Drug Enforcement Administration spokesman Rusty Payne. “When we’re taking this much out of the supply chain, it’s a huge deal.”

Reporters were shown barrels of white and yellow powder that were found in a laboratory on a small ranch outside of Guadalajara, Mexico’s second-largest city.

The Mexican army said troops received several anonymous tips and found the massive drug stash in the township of Tlajomulco de Zuniga, near the Jalisco state capital of Guadalajara. The army statement called the seizure “historic,” implying it was the largest on record for the armed forces.

There were no people found on the ranch or arrests made, although it appeared 12 to 15 people worked there.

The previous biggest bust announced by the army came in June 2010, when soldiers found 3.1 metric tons (3.4 tons) of pure meth in three interconnected warehouses in the central state of Queretaro.