President Donald Trump participated in the first G7 working session, seated around a large round table with other leaders, after taking part in a photo opportunity that served as the official welcome for the G7 leaders. The theme of the first session was "Global Economic Outlook."

Trump did not answer shouted questions from reporters at both events.

Canadian Prime Minister Mark Carney took the opportunity to deliver remarks that highlighted the G7's history of collaboration and described the current state of global affairs as a "turning point in history."

"We're meeting at one of those hinge moments, those turning points in history. The world is more divided and dangerous. Hostile states and terrorists expanded their capabilities in their reach, threatening global security and our local communities. Global commerce, energy systems, even intelligence, are all being rewired," Carney said.

"We will have open, frank discussions over the course of the next two days. We might not agree on absolutely every issue, but where we will cooperate, we will make an enormous difference, for citizens, and for the world and bring the next era of prosperity I hope to the benefit of those we serve," Carney continued.

-ABC News' Kelsey Walsh

President Trump was asked on Monday multiple questions by reporters about the conflict between Israel and Iran, including what he's heard from the Iranians.

"They'd like to talk, but they should have done that before," Trump responded. "They had 60 days. And on the 61st day I said, 'We don't have a deal.' They have to make a deal. And, it's painful for both parties, but I'd say Iran is not winning this war. And they should talk, and they should talk immediately before it's too late."

Another reporter asked Trump what it would take for the United States to get involved in this conflict militarily.

"I don't want to talk about that," Trump said.

President Trump, participating in a bilateral meeting with Canadian Prime Minister Mark Carney as world leaders gathered in Alberta for the G7 summit, called it a "mistake" for Russia to have been removed from the G8 in 2014 for annexing Crimea.

"The G7 used to be the G8," Trump said. "Barack Obama and a person named Trudeau didn't want to have Russia in. And I would say that that was a mistake, because I think you wouldn't have a war right now if you had Russia in."

"It was a mistake in that you spend so much time talking about Russia. And he's no longer at the table, so it makes life more complicated," Trump added.

Asked later if he believed Russia's Vladimir Putin should have a seat at the table with other world leaders at this week's summit, Trump responded: "I'm not saying he should at this point because too much water has gone over the dam, maybe. But it was a big mistake."

President Donald Trump arrived on Sunday in Canada for a Group of Seven summit, where international leaders are expected to focus on trade, energy and the resolution of conflicts, including Russia’s war in Ukraine.

Trump is scheduled on Monday morning to meet with Prime Minister Mark Carney of Canada, who held their first in-person meeting at the White House last month.

Trump, Carney and other leaders -- from Italy, France, Germany, Japan and the United Kingdom -- are then scheduled to hold several sessions, which will stretch into the evening in Kananaskis, a district in the Canadian Rockies.

President Volodymyr Zelenskyy of Ukraine is also expected to attend the two-day summit.