(CNN) There is growing concern within the US military about the costs of President Donald Trump's proposed military parade and the disruption it could cause.

If Trump insists on a military parade through Washington involving thousands of troops, armored vehicles, missiles and other heavy weapons the event could disrupt crucial military training schedules, according to a defense official directly familiar with the initial planning efforts.

There are also concerns over the cost of the event, and a second defense official tells CNN that the Pentagon is considering seeking out private donations to offset some of the non-military costs of the event. The donations could not cover military salaries or the cost of moving equipment but they could be used to pay for other aspects of the parade.

There are no firm cost estimates until President Trump orders the military to stage a specific event, but very preliminary estimates suggest the cost could run between $3 million and $50 million, the first official said, emphasizing that nothing is certain at this point. There is no money currently allocated for a parade in the defense budget. Budget director Mick Mulvaney said Wednesday that he has seen estimates that a military parade could cost $10 million to $30 million.

On wider concerns about a large scale parade, "we don't have troops and units sitting around waiting to do a parade," the first defense official said. A large parade could require weeks of preparation, including the early shipment of equipment such as tanks, and personnel would need to arrive days ahead to be ready to man the gear during a parade.

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