Prime Minister Stephen Harper greets U.S. President Barack Obama upon his arrival on Parliament Hill in Ottawa on Thursday. (Fred Chartrand/Canadian Press)

Barack Obama and Stephen Harper said they will establish a clean energy dialogue and work on easing cross-border bottlenecks following a meeting on Thursday in which the U.S. president also stressed he did not press the prime minister to extend Canada’s combat role in Afghanistan.

Harper said he and Obama, in Ottawa on his first foreign visit since becoming president, outlined three main priorities of the bilateral relationship — working together to restore economic growth, a new initiative on environmental protection and a commitment to stabilize Afghanistan.

During a news conference on Parliament Hill, both leaders said the new environmental initiative will include development of clean energy science and technologies that will reduce greenhouse gases and combat climate change.

U.S. President Barack Obama signs a guest book in the Rotunda area of Parliament Hill shortly before noon Thursday. (CBC)

With Afghanistan becoming a focal point of Obama's foreign policy, there have been questions as to whether the U.S. will ask Canada for a longer combat commitment past the 2011 deadline.

"I certainly did not press the prime minister on any additional commitment beyond the ones already made. All I did was to compliment Canada on not only the troops that are there … but also the fact that Canada's largest foreign aid recipient is Afghanistan," Obama said.

"We just want to say thank you."

On the controversial "Buy American" provision included in the U.S. stimulus package, Obama said he made clear that those measures will be consistent with Washington's obligations under the World Trade Organization and the North American Free Trade Act.

"I provided Prime Minister Harper an assurance that I want to grow trade, not contract it," Obama said.

Harper said those agreements do allow domestic purchasing preferences, but pointed out they are not allowed without limits.

"We have agreed in the G-20 countries to stimulate the global economy, not just benefit ourselves. If we choose to benefit ourselves at the expense of others, we will deepen the global economic crisis," Harper said.

Obama said the two leaders also discussed the issue of border security and how both governments could use some stimulus and infrastructure spending to potentially ease the bottlenecks at the border.

"Now, we've got very real security concerns, as does Canada, but I think that it is possible for us to balance our security concerns with an open border that continues to encourage this extraordinary trade relationship in which we have $1.5 billion worth of trade going back and forth every single day," Obama said.

U.S. President Barack Obama, left, walks with Prime Minister Stephen Harper through the Hall of Honour at Parliament Hill in Ottawa on Thursday. (Jim Watson/AFP/Getty Images)

Harper said that he wanted to make it clear to the U.S. that since the Sept. 11, 2001, attacks, Canada has made significant investments in security along the border and that Ottawa takes security concerns as seriously "as our American friends."

"Obviously we've been concerned with the thickening of the border. The key is to look at how we can deal with security in a way that doesn't inhibit commerce," Harper said.

The U.S. president also mentioned his personal relationship with Canada, saying his brother-in-law lives in the country and that he has two key staff members who are Canadian.

"I love this country and I think we could not have a better friend and ally," Obama said.

Following the news conference, Obama made a surprise visit to the city’s Byward Market to sample a BeaverTail, an Ottawa delicacy made of deep-fried dough. He also stopped at a local mall to buy a maple leaf cookie for his daughters.

Obama landed at Ottawa International Airport around 10:30 a.m. and arrived just before noon by motorcade at the Centre Block rotunda of Parliament Hill.

'Great honour'

Harper and Obama met privately for 33 minutes, a session originally slated to last only 10 minutes. They then moved on to a meeting and working lunch with their staff teams.

Cameras were briefly allowed into the prime minister's office, where both men were seen smiling and chatting.

"Thank you so much for having me," Obama said to Harper as they stood and shook hands for the cameras.

"It’s a great honour to have you here on your first visit. We really appreciate it," Harper said.

U.S. President Barack Obama buys a maple leaf cookie for his daughters at a mall in Ottawa. (Jim Watson/AFP/Getty Images)

A senior PMO official said the private meeting gave the leaders a chance to establish a "good rapport. This was a good start and bodes well for the rest of the day."

When the president arrived on the Hill, he waved to a cheering crowd of an estimated 2,500 people who had gathered in front, hoping to catch a glimpse of the U.S. leader.

Clary Fraser, who drove from Toronto to take in the moment, said he was in Birmingham, Ala., during a tragic race bombing in 1963.

"No one, no one in the world would have dreamed, could suggest that there would one day be a black president of the United States," Fraser said.

Honour guard

Obama had been greeted at the airport by Gov. Gen. Michaëlle Jean after Air Force One touched down.

An RCMP honour guard lined the airport tarmac as Obama was welcomed by the Governor General and other officials, including Foreign Affairs Minister Lawrence Cannon and Michael Wilson, the Canadian ambassador to the U.S.

Obama, who was wearing a long, dark coat with a dark crimson scarf tucked into the collar, and Jean, who was wearing a long, charcoal coat and matching hat, smiled and chatted as they walked side by side toward the airport terminal.

Crowds of people braved the light snow and chilly, damp weather to line the heavily guarded and barricaded streets of Ottawa. Busloads of police started arriving in the downtown area around 7:30 a.m. ET to start shutting down the streets.

The RCMP arrested a 20-year-old man Thursday morning who apparently tried to jump a barrier set up on Parliament Hill. The man was being questioned.

Meeting with Ignatieff

Yellow-jacketed officers patrolled the streets by foot, scanning the sidewalks for any suspicious items.

Obama did not address Parliament during his six-hour visit, but met with Liberal Leader Michael Ignatieff at the airport before he departed for Washington around 5:30 p.m.

With files from the Canadian Press