The U.S. secretary of homeland security doused hopes on Wednesday that the Canadian border will be treated differently than America's beefed-up boundary with Mexico.

"One of the things that we need to be sensitive to is the very real feelings among southern border states and in Mexico that if things are being done on the Mexican border, they should also be done on the Canadian border," Janet Napolitano told a Canada-U.S. border conference in Washington, D.C.

The day-long Brookings Institution event featured dozens of participants from both countries discussing ways in which the movement of goods and people across the Canada-U.S. border could be facilitated. Napolitano's remarks closed the event.

"We shouldn't go light on one and heavy on the other," she said of the Canadian and Mexican borders.

"This is one NAFTA, one area, one continent, and there should be parity there. I don't mention this to suggest that everyone in this room will agree with that, I mention it to suggest it's something I have to deal with, and so I ask for your sympathy."

Napolitano's comments came after she testified at U.S. Senate hearings into growing drug violence at the U.S.-Mexican border that's prompted U.S. President Barack Obama to redeploy more than 500 federal agents to border posts and the Mexican interior.

He's also redirected $200 million US to combat smuggling of illegal drugs, money and weapons.

Napolitano told the hearing it would probably take weeks to complete a contingency plan for sending U.S. National Guard troops to border areas.

The United States is concerned that drug wars that killed 6,000 people in Mexico last year will spill across the border. Mexico says U.S.-acquired guns are fuelling the violence.

No more delay on passport requirements

Napolitano, a former governor of Arizona, spoke at the Brookings conference of the close relationship between the U.S. and Canada, particularly among those living in border communities.

"It's as though there's not a border at all," Napolitano said.

"People are used to going back and forth, and the hockey teams go back and forth.... People just don't think of it as two different countries. But the reality exists that there's a border there."

She also said there would be no further delay of the Western Hemisphere Travel Initiative, which as of June 1 will require adults entering the United States from Canada, the Caribbean, Bermuda or Mexico to present a passport. That phase of the initiative has been delayed several times.

Napolitano's comments came despite a Democratic congresswoman's remarks to the conference earlier in the day that neither the U.S. nor Canada was prepared to meet the June deadline.

"There is a lot of concern on both sides of the border.... Are we really ready?" Napolitano acknowledged. But she told the conference that "we are prepared to go forward in June."

To delay the initiation date again would send the wrong message to both Canadians and Americans that neither country is serious about getting the program up and running, Napolitano said.

"We're exploring what we can do with Canada to publicize that this deadline is coming. It is real. And it really goes to that change of culture — there is a sense in some places that, 'We've always gone back and forth. Why do I need to get a passport?' and we're going to get some of that," she said.

"But it is a real border and we need to address it as a real border."