WASHINGTON (AP) — Orders to U.S. factories for long-lasting manufactured goods rose in March, but a key category that tracks business investment plans was weak for a second month.

Orders for durable goods increased 0.8 percent, rebounding partially from a 3.1 percent tumble in February, the Commerce Department reported Tuesday. The result was fueled by a jump in demand for military equipment, a volatile category.

Excluding defense, durable goods orders would have fallen 1 percent in March.

Demand in a category that serves as a proxy for business investment plans was flat in March after a 2.7 percent drop in February.

Jenifer Lee, senior economist at BMO Capital Markets, called the March orders report "very disappointing," with business investment soft as the first quarter ended.

She noted that the investment category has risen only once in the past five months. The flat reading in March indicated "little-to-no momentum" heading into the second quarter, she said.

Manufacturing has been under pressure for the past year, reflecting global weakness, a strong dollar and falling oil prices.

Prospects for 2016 remain uncertain. Some economists believe that U.S. factories should see a pickup in demand since the dollar has stopped strengthening against other currencies. The global economy also seems to have stabilized after a shaky start to the year. But other analysts are uncertain about how long it might take for manufacturing to bounce back.

For March, overall defense orders surged by 38.6 percent, led by a 65.7 percent increase in demand for military aircraft and parts. But the 1 percent decline in demand outside of defense reflected weakness in a number of areas.

Orders for commercial aircraft, another volatile category, fell 5.7 percent following a 26.6 percent drop in February. Orders for motor vehicles and parts dropped 3 percent. Demand for appliances and other electrical equipment also declined 3 percent.

Demand for primary metals such as steel rose 0.8 percent, and demand for machinery was up 0.5 percent.