Pressure is mounting on Amazon to enter talks with its workers’ union, as employees from seven U.S. warehouses walked off the job this morning, during a peak period due to the holiday shopping rush.

Warehouse workers in cities like New York, Atlanta, and San Francisco are participating in what the International Brotherhood of Teamsters union has described as the “largest” strike at Amazon, representing around 10,000 workers at 10 of the company’s facilities.

“If your package is delayed over the holidays, you can blame Amazon’s insatiable greed,” said the union’s president, Sean O’Brien, late last night.

“We gave Amazon a clear deadline to come to the table and fairly address our members. They ignored it. They are responsible for this strike.”

The union had given Amazon a deadline of December 15 to begin negotiations, and workers at the warehouses recently voted in favor of striking.

Amazon says no impact on operations
Amazon claims it does not expect any impact on its operations. Union members make up only 1% of Amazon’s workforce. Areas like New York City have many warehouses and smaller pickup points that can help Amazon mitigate any potential impact from the strike.

Observers say Amazon is unlikely to sit down for negotiations, as this could lead to further protests. The company employs more than 1.5 million people worldwide and has stated that it prefers to have a direct relationship with its staff.