There are nearly 12,000 gun-related murders every year in the U.S., with crimes like robbery, illegal possession, sexual assaults and others often involving illegally obtained handguns.

Action is needed, as laws regulating gun sale and possession vary from state to state. States that feature the loosest gun control laws threaten not only their own residents, but also the population of the U.S. and beyond.

A study to be released this week by Mayors Against Illegal Handguns – which is a campaign led by 596 mayors nationwide, including Tampa mayor Pam Iorio – found that half of the 43,000 guns traced to crimes last year came from the top 10 states with the weakest gun control laws, according to the New York Times.

“A state’s gun laws are only as good as the weakest link in the national chain,” said James Alan Fox, a criminology professor at Northeastern University, to the Times. “A state with weaker gun laws becomes a supplier for states with stronger laws.”

Criminals can easily cross back and forth unsecured state borders to sell guns on the black market.

Since Mexico launched its crackdown on criminal cartels in 2006, more than 28,000 people have died in the resulting violence. According to the Bureau of Alcohol Tobacco and Firearms, 90 percent of the weapons used by cartels have come from the U.S., many of which were legally bought in states with lax gun control laws.

Mexican lawlessness is beginning to resemble an insurgency, and bullets have even flown across the border and hit buildings like El Paso City Hall.

Even more troublesome is the possibility that terrorists may try to exploit this weakness by purchasing guns to massacre innocent people.

While the second amendment correctly guarantees the right to bear arms, which is important for Americans’ self defense, lax gun laws are more likely to put the weapons in irresponsible hands.

Leaders of the National Rifle Association have rejected these notions as biased – their chief lobbyist Chris W. Cox labeled it a “cute little P.R. stunt” – and said more policing will suffice.

But it’s hard to disagree that more stringent gun-purchase requirements, or even closing loopholes that allow gun purchases at gun shows without a background check, would be a good place to start.

In light of new information that confirms many long-held suspicions, more universal gun laws need to be considered on a federal level if individual states refuse to acknowledge their responsibility in the team effort to reduce gun crimes.