News 12 is learning more about the so-called "mystery flights" carrying undocumented children from the southern border to Westchester in the middle of the night.

The flights have been coming to Westchester County Airport for some time as part of President Joe Biden's immigration plan, even though it is just getting attention now.

Former Westchester county executive and Republican candidate for governor Rob Astorino tweeted out video Monday claiming those flights were allegedly dropping off migrant children at Westchester County Airport and that it had been happening for months.

The federal Department of Health and Human Services confirms the flights are reuniting the minors with their parents after getting separated while illegally crossing the border.

"All I know is that we're not the only airport going through this. There are a lot of places around the country," said Westchester County Executive George Latimer.

This is part of President Joe Biden's immigration plan of reuniting undocumented immigrant families after former President Donald Trump's "zero tolerance" policy separated families to dissuade people from entering the country illegally.

The flights don't surprise Luis Yumbla, a Port Chester Immigrant Defense board member. The organization reconnects these families.

He also says they've been happening for months.

"Lately, it's happening more because more people are crossing the border and more people are in the shelters," he says.

Even though the flights are legal, according to the HHS, local Republicans aren't happy.

Astorino is questioning if county officials knew about the flights, if there was a COVID-19 risk, and where the passengers were headed.

"This is a question of public safety, of public health, and the public's right to know," says Astorino.

Latimer said he has not yet heard from the HHS, but he was submitting a list of questions to the agency, and promises to make the answers public as soon as possible.