Staff at the Smithsonian National Zoological Park (SNZ) in Washington D.C. are very busy providing around-the-clock care for two tiny panda cubs born earlier this week.

Giant pandas give birth to twins about 50 percent of the time, and only three pairs of twins have ever been born in the United States. It's risky business, so the zoo opted to partially hand-rear the pair to give the newborns the best chance of survival.

After a long first night, we're happy to report the twins are doing well. And for your viewing pleasure, SNZ has released the unbearably cute video of one cub's first check-up.

The panda team will alternately swap the cubs, allowing one to nurse and spend time with mother Mei Xiang, while the other is being bottle-fed and kept warm in an incubator. With the babies weighing in at just 86 and 132 grams respectively, it's imperative that both get ample attention.

"There are only two other female giant pandas who have successfully reared twins and it required a lot of human support," the team explains. "The cubs are doing well but the panda team had a challenging night."

When keepers initially tried to swap the cubs, Mei Xiang would not set down the baby she had in her possession. Rather than force the exchange on the tired mother, cub number two was kept in the nursery overnight for bottle and tube feedings. 

"Our goal is for each cub to spend an equal amount of time with their mother," says the team. "The newborn cubs are vulnerable and this first week is incredibly important. Our concern now is whether Mei Xiang will allow the panda team to consistently swap the cubs. [But we've] developed a few different strategies and will continue to try different methods of swapping and hand-rearing. A lot will be dictated by Mei Xiang."

Check out footage of the first cub being born:

And five hours later, twin number two!