Authorities say the arrests of three men who allegedly sold casings for 23 hand grenades this week in metropolitan Phoenix is a reminder that the illegal market for explosives isn't isolated to Mexico.
Investigators say the three men sold grenade shells to undercover police for $400 each and were under the impression that the components were going to be smuggled into Mexico, where the government there is waging war against drug cartels that have sought heavier weapons to battle back against the military.
Even though the grenade casings were suspected to have been bought legally at a military surplus store and lacked key parts to make them functioning explosives, police said the men broke the law by saying the shells were live explosives.
‘‘They didn't state that anything was missing. That's something we found out (later) through our bomb technicians,'' said Harold Sanders, a spokesman for the Arizona Department of Public Safety, which is leading the investigation.
Federal agents who investigate explosives cases say they will periodically come across people wanting to buy or sell grenades in Arizona, one of the country's busiest hubs for marijuana smuggling and where drug cartels send people to buy guns that are later sneaked into Mexico.
While many cartel grenades are black-market weapons stolen from foreign militaries and sold by arms dealers, agents say drug organizations that want to assemble their own explosives will sometimes turn to criminals in the United States for help.
‘‘We are part of this,'' said Bill Newell, special agent in charge of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives in Arizona and New Mexico. ‘‘As a border state, we are part of this ongoing effort on the part of the government of Mexico to defeat the violent drug cartels. For us to sit back and think, 'Well, it's just across the border. What do we care?' We must care, because if they lose, we lose.''
Even though people will periodically seek or buy grenades illegally in Arizona, authorities say pipe bombs were by far the most common illegal explosive device in the state. Still, federal agents say the threat posed by grenades is real.
In a 2004 sting, for instance, a man who claimed to work for Mexican mafia members involved in drug trafficking told an undercover agent that he would pay $200 each for 24 grenades. A week later, the man met undercover agents in Phoenix and asked whether they had grenades capable of blowing up two vehicles, according to a report by federal agents.
He paid $6,000 for a box of 30 grenades. Once arrested, the man told authorities that he was going to sell the grenades to a man who lived in Nogales, Mexico, and that the grenades would then go to the Mexican state of Sinaloa for use by mafia members, the report said.
Forty-eight-year-old Sergio Noriega pleaded guilty to federal weapons charges and was sentenced to 30 months in prison.
In this week's bust, the three suspects - two illegal immigrants from Mexico and a third whose immigration status was unknown - sold seven baseball-style and 16 pineapple grenades during undercover police busts on Monday and Tuesday in metro Phoenix.
It's not yet known whether the suspects had ties to drug or immigrant smugglers, Sanders said.
Federal agents became more concerned about grenades after learning that the explosives, once isolated to southern Mexico in the early days of that country's drug war, have gradually moved northward and surfaced near the U.S. border.
The only reported instance of a military-grade grenade with suspected ties to Mexican drug cartels or their associates being used in an attack in the United States was in January at a south Texas bar. Even though a suspected gang member threw the grenade into the bar, the grenade didn't explode because its thrower neglected to pull a second safety clasp. No one was injured.
Although the grenade thrower wasn't believed to have made the attack on behalf of a cartel, investigators suspect the source of the explosive was a Mexican drug trafficker or an associate.
Grenade bodies are sold legally at gun shows and military surplus stores, but it's illegal to turn them into live explosives or pass them off as functioning grenades.
Newell, the ATF boss for Arizona and New Mexico, said the state police in Arizona did the right thing in busting the three men this week in metro Phoenix, even though it turned out their grenades weren't capable of exploding.
‘‘They have to assume they are real,'' Newell said.