Rolling south across the Lincoln Juarez International Bridge, the 2009 Honda CRV looked much like all the other vehicles headed for Mexico. Who knew there was $300,000 in cash stuffed behind the dashboard?

Certainly not the Customs and Border Protection officers who pulled the Honda over for a "secondary examination" on Oct. 27.

But when the officers tumbled to the wads of cash, the driver and passenger -- both Mexican nationals in their 20s -- knew they were in trouble. It's illegal to cross the border without "declaring" amounts of cash over $10,000.

Most likely, this mother-lode of cash came from a Mexican drug cartel trying to "repatriate" some of the profits from its U.S. operations. Doubtless the cartel can write off the $300,000 loss as a "cost of doing business," but it couldn't have been pleased to see the CBP walk off with its payday.

Such "small" victories in the border battle are important. CBP and the Border Patrol are under no delusion that they can seal the border or shut down the criminal cartels whose operations stretch from the southernmost reaches of Mexico to the northernmost U.S. cities.

They do know, however, that they can make a difference. Effective border security is an essential component of preserving our nation's sovereignty and safety. The men and women guarding the Laredo "port of entry" are doing much more than just sticking a finger in the dike.

Every time the CBP or Border Patrol (both are part of the Department of Homeland Security) makes a bust at the border, there is a chance it will produce information that will lead up the food chain to a "big fish" in the criminal enterprise.

It may also add a piece to the puzzle in understanding the inner workings of the cartel networks that funnel cash, people, drugs and guns across the border.

Moreover, effective interdiction at the border is disruptive. It can force the cartels to shift their smuggling routes and tactics. And every time criminals must adjust operations, there's a chance they'll make a miscue that law enforcement can exploit.

Folks at the Laredo Port of Entry understand that, to take down the cartel network, they must link their efforts with those of other federal, state and local law enforcement agencies.

And CBP is keenly aware the maximum effectiveness also requires working with authorities on the other side of the border. Across the border in Nuevo Laredo, the cartel profile is so prominent that the national government disbanded the local police and sent in the military to watch over the town -- and to monitor the Mexican border-crossing authorities. Progress there is contingent on the Mexican military's ability to restore order and track down cartel kingpins.

While the United States is not yet winning the border war, the CBP and the Border Patrol are doing their part. As the federal government faces the prospect of across-the-board spending cuts, politicians in Washington ought to be asking themselves, "Does that make sense, when it comes to border security?"

Cuts to CBP would, beyond doubt, directly weaken operational activities on the border. That may mean fewer dog teams on the line sniffing out smuggled drugs, cash, guns and aliens.

It may mean fewer primary inspection lanes, thus dramatically impeding the flow of commerce. Or it could mean fewer liaison teams coordinating with Immigration and Customs Enforcement or the Drug Enforcement Administration.

Any way the cuts come down, they will mean less border security. No one in Washington should be willing to accept that.

James Jay Carafano is a senior research fellow for national security at the Heritage Foundation.