Drug smuggling across the border with Canada is much more prevalent than indicated by the number of cases in which drugs have been seized, according to a federal report from November.
Less than 1 percent of the 4,000-mile border is considered under the operational control of U.S. border officials, a General Accountability Office report found this month. Most areas of the northern border are remote and inaccessible by traditional patrol methods, the report said.
Pennsylvania's U.S. Sen. Bob Casey, who requested the study, said that's "not acceptable."
"A multi-pronged attack is required to catch drug smugglers or terrorists before they can cross the border over Lake Erie into Pennsylvania or other northern states," Casey said.
Sen. Herb Kohl, from Wisconsin, said northern border smuggling "is a growing problem."
"We hear about the path of illegal drugs form Chicago and the spread of meth from our western borders," Kohl said, "but securing our northern border is too often overlooked."
Customs and Border Protection said it believes it can detect illegal entries and respond to and deal with them on only about 32 miles of the northern border. The Border Patrol was aware of all illegal border crossings on only 25 percent of the border, or 1,000 miles, the GAO report said.
The effort by the Democratic senators comes after the Department of Homeland Security said it added Border Patrol agents, new technology and more. More than 2,200 agents are assigned to the northern border, a 700 percent increase since the 2001 terrorist attacks. The tools include thermal camera systems and mobile surveillance systems.
Recent U.S.-Canada agreements allow law enforcement to share information and cross-training involving the Royal Canadian Mounted Police, the U.S. Coast Guard, Customs and Border Protection and Immigration and Customs Enforcement.
Homeland Security spokesman Adam Fetcher said the agency will review the letter and respond directly to the senators.
"We have made critical security improvements along the northern border - deploying additional Border Patrol agents, technology and infrastructure, and, just two weeks ago, we successfully completed the first long-range CBP Predator-B unmanned aircraft patrol under expanded (Federal Aviation Administration) authorization that extends the range of our approved airspace along the northern border by nearly 900 miles," Fetcher said.
Last week, President Barack Obama and Canada Prime Minister Stephen Harper announced an agreement for a "perimeter approach to security, working together within, at and away from the borders of our two countries."
Still, the senators said more should be done.
"We have the technology to prevent drug smuggling from low-flying aircraft, now we need to use it," said Sen. Sherrod Brown, of Ohio.
Sen. Kirstin Gillibrand, of New York, said the problem "must be fought at its source."
Some members of Canada's Parliament have dismissed American worries about security along the countries' border. Immigration Minister Jason Kenney has said Canada has improved security.
Use of radar in Washington state from 2005 to 2008 by the Departments of Defense and Homeland Security was considered a success in identifying low-flying, drug-smuggling aircraft that hadn't been previously identified, said Sens. Charles Schumer, of New York, and Jon Tester, of Montana.
"Given what is at stake in combating illegal cross-border activity, and given its past success, I write to ask your agencies to coordinate in determining whether there are any available military technological assets anywhere around the world that can be more effectively deployed along our northern border to combat drug smuggling," the senators wrote in the letter.