• Amazon workers in several warehouses went on strike on Thursday.
• The strike comes in the middle of Amazon’s most important holiday shopping and shipping season.
• Amazon said it sees no impact on its operations.

Amazon workers at seven Amazon fulfillment centers went on strike Thursday, although the retailer said it saw no impact on its holiday delivery operations.

According to a statement from the Teamsters, which represents the employees, the workers are quitting their jobs after Amazon refused to negotiate a contract with them.

According to the Teamsters, the strike will affect three Amazon fulfillment centers in Southern California and one each in New York, Atlanta, San Francisco and Illinois. The union said it would also set up picket lines at other Amazon facilities.

The promotion comes in the middle of the important Christmas shopping season. Amazon’s highest quarterly sales have historically occurred in the last three months of the year. This year, that period included the company’s Prime Day in October as well as Black Friday deals.

“If your package is delayed during the holidays, you can blame Amazon’s insatiable greed,” Teamsters general president Sean O’Brien said in the statement.

O’Brien said the Teamsters “have given Amazon a clear deadline to come to the table and do what’s right for our members.”

“They ignored it,” he added.

An Amazon spokesman said Thursday morning that the company’s operations had not been affected by the strike.

Spokeswoman Kelly Nantel said in a statement that the Teamsters recruited non-employees to participate in the strike and intimidate Amazon employees. When Business Insider asked for evidence to support these claims, an Amazon spokesperson said: “We know our employees and know they are not out there. Our employees repeatedly allege to management that they are facing harassment from activists.”

“We appreciate our team’s great work serving our customers and communities and remain focused on getting customers their holiday orders,” Nantel said.

Workers at some Starbucks stores also prepared for a possible strike this week. On Tuesday, a union representing about 10,000 baristas said its members had voted to authorize a strike, although negotiations with Starbucks continued and no strike date had been set.

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