It's 9:15 a.m. and Bryan Stern is waiting outside a Kyiv hospital. The sound of shelling in the distance forces him and his team to hurry. They need to get two premature babies into an ambulance and out of the besieged Ukrainian capital.

This is Operation Gemini, named for the American twins he has been tasked with evacuating.

Across the border in Poland, their father, Alex Spektor, is waiting to meet his babies, who were born via a surrogate. His voice is thick with emotion and fatigue as he relays the latest over the phone.

"They've been on the road for about six hours, and they have five more hours after that," he says.

"They will be put into the NICU immediately. We don't want to slow down that process."

His twin sons, Lenny and Moishe, were born premature 10 days earlier in Kyiv, just after Russia began its attack on Ukraine.

They were too small to move in the days after they were born into a war zone. But as they grew stronger, Kyiv grew weaker. Now, they are making the run for the border with Stern and his specialist evacuation team of U.S. Army veterans.

It's a treacherous journey that will include Russian shelling, complex border crossings and a snowstorm.

A desperate search for help.

Spektor and his partner, Irma Nuñez, live in Chicago but for weeks had been watching the growing tension between Ukraine and Russia as their surrogate, Katya, was approaching her due date.

Spektor was born in Kyiv when it was part of the Soviet Union, and his family came to the U.S. as refugees.

When his sons arrived early in Kyiv and needed vital care to survive, there was hope they could be moved to a city farther from the fighting. But transporting such fragile cargo would be a delicate move and require special medical care, so the babies stayed in the capital.

Then the situation became more desperate, and so did Spektor and Nuñez. Spektor flew to Poland and relayed messages back home. They reached out to anyone who might help.

Stern stepped in. The Army and Navy veteran runs a nonprofit specialist extraction team from Florida called Project Dynamo that goes into war zones and rescues those trying to escape.

Stern has been exfiltrating people, many of them U.S. citizens, from some of the most besieged cities in Ukraine ever since the war broke out.

As Operation Gemini begins on Monday morning, Stern starts to relay updates to Spektor and NPR.

The team also includes two doctors, two neonatal specialists, a nurse and a Ukrainian ambulance crew.