Saying strike is "imminent," Atlanta-based UPS gets a Friday deadline from union to come up with a better contract

Frustrated by an “appalling counterproposal” earlier this week, the head of the union representing 340,000 UPS workers said a strike is imminent and gave the shipping giant a Friday deadline to improve its offer.

The International Brotherhood of Teamsters walked away from negotiations Wednesday, demanding that UPS give its “last, best, and final offer” no later than June 30.

Teamsters officials did not say what time the Friday deadline was or what actions it might take if it is not met.