United Airlines, faced with a steep drop in travel demand due to the coronavirus crisis, is aggressively cutting April and May flights, freezing hiring and offering employees voluntary unpaid leave.

The airline announced the unprecedented steps, the first by a U.S. airline since the outbreak began, in a memo to employees Wednesday.

"Due to decline in demand flowing from the impact of COVID-19, we’re taking additional steps to reduce our international and domestic schedules,'' United CEO Oscar Munoz and President Scott Kirby said in the memo.

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The airline did not provide specific routes being targeted but said it is reducing its international schedule by 20%, including previously announced cuts to China and Hong Kong, and 10% in the United States. An undisclosed number of wide-body planes, used on long-haul flights, will be parked.

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United said it will not abandon any cities but is temporarily cutting some routes and frequencies on other routes.

With less flying, United said it will be offering employees voluntary unpaid leave. The airline is also freezing hiring through June and delaying the payment of merit raises for management and administrative employees.

Whether additional moves are necessary will depend on the spread of the disease and traveler anxiety around it.

"We sincerely hope that these latest measures are enough, but the dynamic nature of this outbreak requires us to be nimble and flexible moving forward in how we respond,'' the executives said.

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