WASHINGTON — US demand for long-lasting manufactured goods rose sharply in December on strong gains in volatile aircraft orders. But companies slowed their orders of goods that signal investment plans, indicating manufacturing could stay choppy.

The Commerce Department said Monday that overall orders for durable goods increased 4.6 percent in December compared with November. The gains were led by a 56.4 percent increase in military aircraft orders and a 10.1 percent increase in commercial aircraft orders.