Conservative Leader Stephen Harper is defending his plan to make it illegal for Canadians to travel to areas controlled by terrorist organizations and calling out the NDP and Liberal leaders for opposing military action against ISIS in Iraq and Syria.

Harper told a dinnertime crowd at a rally in Brampton, Ont., that Canadians from those countries had told him, “if you don’t fight ISIS and you just drop humanitarian aid, you’ll be dropping aid on dead people.”

Harper said that both NDP Leader Tom Mulcair and Liberal Leader Justin Trudeau have promised to remove troops and aircraft from the international force.

“For a prime minister, there is no more difficult decision than sending young men and women into harm’s way in a dangerous part of the world, but these are the decisions you have to be able to make from time to time,” Harper said.

“Our opponents are simply not up to it.”

Earlier in the day, the Conservative leader dismissed concerns that his proposed ban on travelling to areas controlled by terrorist organizations would limit the rights of Canadians, stressing that there are very few reasons for Canadians to be visiting these areas.

"Frankly, these are not areas where families go. These are areas where we know why people are really going: They are going for terrorist training," Harper said. "That is not a human right in this country."

The Conservative leader announced the proposed ban on Sunday, explaining that, if passed, Canadians who travel to listed areas would have to prove they were visiting for humanitarian reasons, or in a professional capacity as a journalist.

"This is limited to only those areas that are only under the control of terrorist organizations, we're talking about a very small number of areas in the world," Harper said Monday, citing parts of Iraq and Syria as examples.

Earlier on Monday, Liberal Leader Justin Trudeau criticized the ban as nothing more than "electoral posturing." He also accused the Conservatives of not adequately thinking through the policy.

"Canada is a country that respects people's rights," he said at a campaign stop in Montreal. "Anytime a government chooses to limit those rights, it has to be able to answer very direct and complete questions about why it's necessary, how it will work, and about what the clear plan is, and Mr. Harper has done none of that.

"It's not a serious plan."

On Sunday, NDP Leader Thomas Mulcair questioned whether such a policy would make a difference.

Speaking in Vancouver, Mulcair told reporters that there is "little evidence" such a law would have any effect.

"I don't know of too many flights between Toronto and these war zones," he said. "Most of them are going through other countries, so it won't make a big difference, practically speaking."

'What does it offer?'

Sukanya Pillay, executive director at the Canadian Civil Liberties Association, said the government has already enacted legislation that makes it a crime to travel abroad to participate in a terror offence, so it remains to be seen what the new ban would add.

"What does this new proposed ban do? What does it offer? We're not quite sure," she told CTV News Channel. "But one thing we know, a blanket ban raises a concern for us. It limits mobility rights, (and) it might limit liberty and equality rights."

She said the proposed ban is also troubling, as it requires the accused individual to prove that they did nothing wrong. "Why should people have to prove that they're going somewhere for a legitimate reason?" she said.

Pillay added that mobility rights are entrenched in a free and democratic society, and are contained in the charter.

"If we're going to limit that right, we have to have a really good reason to do that," she said.

She added that many questions remain on how the ban will be enacted, including who will decide which countries make the list, who will listen to people's explanations on why they are travelling to a particular region, and if there will be an appeal process.