More than 33,000 Boeing employees ended their strike a month ago. But planes have only just recently started moving along the assembly lines that were idled by the two-month work stoppage.

Boeing restarted production of its best-selling 737 MAX jetliner last week, about a month after the end of a seven-week strike by 33,000 factory workers, according to three sources familiar with the matter.

Boeing said Tuesday it has restarted production of its bestselling 737 MAX jets, nearly three months after the jet makers' machinists union began a debilitating strike. Some 33,000 machinists returned to work in November after ratifying a new four-year labor deal.