The main problems were safety, reliability, weight and, especially, sustained operation.

This had never been meant to be a sustained operation, like the one in Afghanistan.

The general suggested that the insurgents were beginning to feel the pressure brought to bear by the sustained operations of the American military.

In 2000, the venue's sustained operation went into question, possibly due to low attendances and high expenses.

"This was not a burst of fire, but a sustained operation over several hours, maybe five hours," one official said.

The horrendous casualties and suffering endured by communist units during these sustained operations was beginning to tell.

It was too small to undertake sustained operations far away from the home support facilities.

Our military action is also designed to clear the way for sustained, comprehensive and relentless operations to drive them out and bring them to justice.

"We simply could not undertake a sustained operation anywhere in the world without the Guard and Reserves."

They are capable of disciplined and sustained operations.