After King Salman of Saudi Arabia came to the throne in 2015 and allowed his favourite son and deputy crown prince, Mohammed bin Salman, to seize the main reins of power in the kingdom, the country has embarked on an assertive foreign and regional policy. The ageing and frail king’s son has upstaged the crown prince and next in line of succession, interior minister Mohammed bin Nayef. That much everyone agrees.

Prince Mohammed bin Salman has accumulated surprising power, in a system where the ruling family normally seeks a careful balance between factions. MbS, as he is known in diplomatic shorthand, aged only 30 in a regime long run by men in their 70s and 80s, is defence minister and economic tsar, as well as overlord of the closely tied areas of foreign and oil policy.

A linear summary of foreign and defence policy in his first year would probably highlight: the Saudi-led air war against Iran-backed Houthi rebels in Yemen launched last March; increased support for Sunni Islamist rebels fighting Bashar al-Assad’s regime in Syria, which is backed by Iran, Hizbollah, the Lebanese Shia paramilitaries and Russia; the break-off of diplomatic relations between Riyadh and Tehran; and, in recent weeks, severing ties with Saudi political, military and media allies in Lebanon.