Why it matters: It's not just corporate employees leaving over the company's aggressive return-to-office policy that Amazon has to worry about. Workers at seven of its facilities walked off the job this morning in what their union is calling the "largest strike" against Amazon in US history. According to the International Brotherhood of Teamsters, which represents 10,000 workers at ten Amazon facilities, warehouse workers in cities including New York, Atlanta, and San Francisco are taking part in the strike.The union had given Amazon a December 15 deadline to begin talks with employees, but the company has refused to negotiate contracts with unionized workers."If your package is delayed during the holidays, you can blame Amazon's insatiable greed. We gave Amazon a clear deadline to come to the table and do right by our members. They ignored it," Teamsters General President Sean M. O'Brien said in a statement."These greedy executives had every chance to show decency and respect for the people who make their obscene profits possible. Instead, they've pushed workers to the limit and now they're paying the price. This strike is on them."The prospect of not receiving your Amazon-bought goods in time for Christmas is certainly concerning. However, Amazon says that it does not expect the strike to impact its operations. A company spokesperson said the union continues to "intentionally mislead the public claiming that they represent 'thousands of Amazon employees and drivers'. They don't, and this is another attempt to push a false narrative."Amazon added that the Teamsters have threatened, intimidated, and attempted to coerce Amazon employees and third-party drivers. It says such actions are illegal and the subject of multiple pending unfair labor practice charges against the union. // Related StoriesStriking during Amazon's busiest period of the year will cause some headaches for the company and customers, but its unionized facilities make up only about 1% of Amazon's hourly workforce, and areas such as New York have multiple warehouses and smaller delivery depots, writes Reuters.Amazon has long faced accusations that its warehouse employees have to endure abusive and dangerous working conditions. The company continues to deny these claims, despite repeatedstrikes by staff.A US senate committee released a report on Amazon's warehouse safety practices on Sunday. It stated that at least two internal studies showed a link between the speed at which workers perform tasks and workplace injuries, but Amazon rejected many safety recommendations as it feared they may reduce productivity.Amazon said the report was "wrong on the facts and features selective, outdated information that lacks context and isn't grounded in reality."November saw the launch of the Make Amazon Pay campaign, in which Amazon workers and allies in more than 20 countries strike and protest against what it calls the company's anti-worker and anti-democratic practices. The actions, which took place over Black Friday weekend, are now in their fifth year.