The Teamsters union is seeking to prevent UPS from using driverless vehicles or drones to deliver packages, the latter of which the parcel delivery company had already performed a number of tests on, reports the Wall Street Journal.

The labor union also wants UPS to ban deliveries after 9 p.m. and add an additional 10,000 workers, according to the Wall Street Journal. In February 2017, UPS successfully tested a drone that launches from atop one of its package cars. This system is designed to autonomously deliver a package while the truck is driven on a route.

Previously, UPS and the Teamsters union recently clashed in December 2017 about the parcel delivery company's decision to bumping up driver workweeks to accomodate holiday deliveries, according to the Atlanta Business Chronicle.

The Teamsters and UPS are currently negotiating one of the largest collective bargaining agreements in the U.S., which covers around 260,000 UPS employees and expires in July, reports The Wall Street Journal.

A recent study by C.J. Driscoll & Associates found the last leg of delivery between distribution centers and buyers has become an issue for e-commerce, which accounted for 11.7% of retail sales in 2016, versus 10.5% in 2015.

In October 2017, the Trump administration moved to establish a coherent federal policy governing the use of drones in delivery applications, according to a presidential memorandum issued last October.