When did the Cold War start?

And if we can't agree on that, how are we supposed to know what a Saudi Arabia-Pakistan mutual defence pact means?

“Give me a one-handed economist,” an exasperated Harry Truman demanded. “All my economists say, ‘on the one hand… on the other.” The 33rd US president should consider himself fortunate not to be surrounded by historians, who seemingly cannot even agree on how many hands there are.

Last month, Saudi Arabia, home to the Middle East’s largest economy, and Pakistan, the Islamic world’s sole nuclear-armed state, signed a “strategic mutual defence” pact. While the two nations have enjoyed a long history of military and economic cooperation, this agreement is something quantitatively new. For one thing, it includes a Nato article 5-like clause, which treats an attack on one as an attack on both.

The timing was not wholly coincidental. While Saudi officials told the Financial Times that they had been working on the pact for “well over a year”, signatures were only added days after an Israeli strike on Hamas targets within Qatar — a move that sent shockwaves around the Gulf.

Not least given that Doha has been designated a major non-Nato ally, and President Donald Trump this month signed an executive order stating that the US would regard any armed attack on Qatar as a threat to American “peace and security”. So there we have it. Doha is doubling down on the US as the ultimate security guarantor while Saudi Arabia hedges its bets.

Except, not so fast. Riyadh continues to discuss a defence deal with the Trump administration, and Crown Prince Mohammed bin Salman is set to visit the White House in November, where reports suggest there will be agreements on military and intelligence cooperation.

I am obviously not an expert in any of these fields — but I do read and listen to what the experts say, and they don’t seem to know either. For instance, does the agreement between Riyadh and Islamabad make nuclear proliferation more likely, or less? No one seems quite sure.