US President Barack Obama has signed an order authorising the government to begin cutting 85 billion US dollars (£56 billion) from federal accounts, officially enacting across-the-board reductions that he opposed but failed to avert.
Mr Obama acted on Friday, the deadline for the president and Congress to avoid the steep one-year cuts.
The president has insisted on replacing the cuts, known as a "sequester" in government budget language, with tax increases and cuts spread out over time. But Republicans have rejected any plan that included tax revenue.
The government says the reductions will soon result in unpaid leave notices to government employees and will trim spending on defence contracts and in domestic government programmes.
Active military personnel and anti-poverty and low-income assistance programmes are largely protected from the cuts.