Javier Milei won Argentina’s presidency last month by wielding a roaring chain saw on the campaign trail to symbolize the slashing he planned for the nation’s government.

On Tuesday, two days after taking office, the self-proclaimed “anarcho-capitalist” unveiled deep spending cuts and a sharp devaluation of Argentina’s currency, carrying the struggling nation of 46 million into a stretch of austerity that he said would bring even more economic pain.

Mr. Milei’s government said it would halt new infrastructure projects; lay off recently hired government workers; reduce energy and transportation subsidies for residents; cut payments to Argentina’s 23 provinces; and halve the number of federal ministries, from 18 to nine.

It said it would also officially devalue the Argentine peso — $1 will now cost 800 pesos, instead of 350 — bringing the government exchange rate much closer to the market value of the peso. The move will likely lead to even sharper price increases in Argentina, which is already suffering under 140 percent inflation.

Mr. Milei and many economists have said that such severe reforms are needed after years of government overspending, but that they would lead to even greater hardship in a nation enduring one of its worst economic crises, including a collapsing currency and rising rates of poverty and hunger.