Foreign reserves surged by US$5.5 billion last month, the biggest gain in a year, Bank Indonesia data showed today.

The previous record was achieved in October. Higher receipts from taxes and services, oil and gas exports, and the government’s withdrawal of foreign loans helped increase the stockpile in December.

The record amount of Indonesia’s dollar stash came even as the central bank intensified efforts to stem the rupiah’s slump fuelled by uncertainties in the US monetary policy and President Donald Trump’s planned tariff hikes.

Last month, the currency tumbled past 16,000 to the US dollar to its weakest level since July, prompting Bank Indonesia to step up interventions in the markets.

The rupiah led declines among major Asian currencies today, falling as much as 0.5% to 16,211 to the dollar in morning trading.

Bank Indonesia may see a higher need for intervention in the near future given “the lower chance of Federal Reserves’ rate cut would drive the greenback higher in the following months,” said Mingze Wu, a currency trader at StoneX Financial Pte Ltd in Singapore.

“Having the warchest growing is always helpful for future intervention needs,” Wu said.

Governor Perry Warjiyo reiterated during the Dec 18 policy rate meeting that the focus of monetary policy remains directed at strengthening the stability of the currency.

Monetary policymakers have kept the benchmark interest rate steady at 6% since October.