US President Joe Biden heads to Ottawa on Thursday to address growing wrinkles in the traditionally smooth relations between the North American neighbors on cross-border migration and the impact of US green tech subsidies.

After a late flight to the Canadian capital, Biden will address parliament on Friday and hold talks with Prime Minister Justin Trudeau.

Ahead of the visit, the two sides are stressing the close integration between their economies and defense structures.

"I think that's going to be the theme of this visit, that we are there making each other stronger and better," Canada's ambassador to the United States, Kirsten Hillman, told CBC.

But only modest, if any, progress is expected on tensions over Biden's Inflation Reduction Act -- a massive program to subsidize and kick start US-based development of electric vehicles and other clean energy products.

"We are looking for more inclusion in exactly those things," a senior Canadian government official told reporters.

"We want a North America that is globally competitive, so that our two economies which are already so integrated, where so many businesses and jobs and supply chains rely on each other, can compete with the world and can be successful together."

Another growing sticking point is the flow of illegal immigrants across the border from New York state into Canada via what's known as the Roxham Road crossing.

Although numbers are far smaller than those coming across the Mexican border into the south of the United States, the resulting political tension in Ottawa echoes the disputes over migration in Washington.

- 'Significant' migration concern -

"We'll be talking about issues of migration," White House National Security Council John Kirby told reporters. "There are more people on the move in this hemisphere than there have been since World War II and that affects both our countries."

Hillman called the border issue "a crisis of very significant proportions."

Canada has pushed the United States to toughen the existing Safe Third Country Agreement (STCA), which is meant to force asylum seekers to make their refugee claim in the first safe country they enter -- which in this case would be the United States.

Last Sunday, opposition leader Pierre Poilievre, from the Conservative Party, accused Trudeau of weakness on trade and migration, saying "Canadians are getting ripped off by the United States."

A third area on the agenda is security.

The US government has been pressuring Canada to increase its defense spending, which in 2022 was just 1.33 percent of GDP. This is scheduled to rise to 1.59 percent from 2026 but that's still well below the NATO alliance requirement of minimum two percent of GDP spending.

The recent alarm over a Chinese balloon that crossed the United States on an alleged spying mission before being shot down, followed by the downing of two more unidentified objects, has put a spotlight on the joint US-Canada air defense system, known as NORAD.

Biden and Trudeau will discuss how to "strengthen our defense through both NATO and NORAD," Kirby said.