Fifteen minutes after takeoff, the call came for Serbia's central bank governor: millions of dollars' worth of gold bars, destined for a high-security Belgrade vault, had been left on the runway of a Swiss airport.

In air freight – despite the extraordinary value of bullion – fresh flowers, food and other perishables still take priority. "We learned this the hard way," Jorgovanka Tabakovi? told a conference late last year.

Serbia's is among a growing number of central banks to hastily amass vast stockpiles of gold, upending decades of conventional economic logic and fuelling an increase in the gold price amid mounting geopolitical tensions. As Washington challenges the US Federal Reserve's independence, sending jitters through financial markets, the price soared to a record $4,643 (£3,463) an ounce this week, and analysts have tipped it to break $5,000 this year.

As Donald Trump shatters the global rules-based order, official institutions (and private investors) are scrambling to buy gold: the share of the asset in central banks' reserves has doubled in the past decade to more than a quarter, the highest level in almost 30 years.

Although this partly reflects the soaring bullion price, experts say central banks are also stuffing their vaults as an insurance policy in a volatile world. Many are also rushing to repatriate gold stockpiles held overseas, and slashing their exposure to the US dollar.

"We have moved from Pax Americana to global discord, geopolitically. It is the law of the jungle when we see what the US are doing," says Raphaël Gallardo, the chief economist at the asset manager Carmignac.

"Investors – private and sovereign – believe their strategic reserves are no longer safe in dollar terms, as they can be confiscated overnight. The dollar is losing the credibility as the nominal anchor of the global monetary system because the Fed is losing credibility, and US Congress is losing its credibility."

Official reserves are a critical piece in the global monetary puzzle. Underpinning national currencies as a kind of safety fund, they are typically made up of currencies such as the dollar, euro, yen and pound, as well as gold, bonds and International Monetary Fund assets. They are used to help maintain investor confidence, and can be deployed to stabilise exchange rates in times of stress.

For much of the past century the dollar has been the primary reserve currency of choice; the grease in the wheels of global finance and the medium of exchange in the majority of world trade.