US President Donald Trump with King Salman bin Abdulaziz al-Saud of Saudi Arabia (centre) and Egyptian President Abdel Fattah al-Sisi in Saudi Arabia last month.

It's that time of year again: 103 years ago this week, Archduke Francis Ferdinand was assassinated in Sarajevo, setting in motion a train of events that led a few weeks later to the outbreak of World War I.