PHOTOS: Zoo Atlanta's giant panda twins reach new milestone

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Photo: Zoo Atlanta 

Zoo Atlanta's 6-month-old giant panda twins have reached a new milestone. 

Ya Lun and Xi Lun are now enjoying all-day play in their dayroom habitat.

The cubs first appeared in the dayroom, located in the Arthur M. Blank Family Foundation Giant Panda Conservation Center, in December, but have been spending more time in the habitat over the last few months. 

MORE: Zoo Atlanta's giant panda twins growing up quickly

Zoo Atlanta said the pandas are now both running and climbing and will soon experience their next milestone, "exploring the great outdoors." They are expected to do so in the next few weeks. 

Ya Lun, 22 pounds, and Xi Lun, 21 pounds, are the only giant panda twins in the United States. They were born on September 3, 2016 and are the sixth and seventh offspring of Lun Lun and Yang Yang. 

Learn more about the giant panda twins here.