The first half of the century, the age of the World Wars and the start of the Cold War, was dominated by the rivalries of those powers.The second half saw the replacement, largely through the agency of those wars, of the European state system by a world system with many centres of both power and discord.
Mr Trudeau, who is in Ireland for a three-day visit ahead of the G20 meeting in Hamburg later this week, enjoyed some downtime with the Irish PM after their day of meetings.
The world leaders both shared photos of their run in Pheonix Park on their Twitter accounts.
The long-term causes of the war can therefore be traced to the forces that impelled the formation of those alliances, increased tensions among the great powers, and made at least some European leaders desperate enough to seek their objectives even at the risk of a general war.
These forces included militarism and mass mobilization, instability in domestic and international politics occasioned by rapid industrial growth, global imperialism, popular nationalism, and the rise of a social Darwinist worldview.
It also said the missile's unique valve-design was only found in Iran. The Pentagon put on display other weapons with designs it said were unique to Iran's defense industry.
Bitter civil war: The Houthi rebels in Yemen are backed by Iran while the government is being supported by a Saudi-led coalition in what is seen as a proxy war. It pointed to a key component of a Toophan anti-tank guided missile and a small drone aircraft, both of which were recovered in Yemen.
4 against the airport and another fired on July 22.
The Pentagon cited corporate logos of Iranian defense firms on jet vanes that help steer the missile's engine and on the circuit board helping drive its guidance system.
The politician, who is a son of an Indian migrant, said it was “unfortunate” Britain had opted to leave the European Union and would be unable to navigate free trade agreements like the one between Canada and the EU until it has formally left the bloc.
"I can't see a scenario where Britain could remain a member of the EU, even in a transitional period, and then negotiate other trade deals on their own," he said.
The Canadian wore mismatched Star Wars socks to meet Mr Varadkar’s predecessor Enda Kenny in May.