Mark Morgan, acting head of Customs and Border Protection, said Thursday that the Trump administration's new asylum rule, unveiled earlier this week, is being rolled out as a small "pilot" and that officials expect it to be blocked in court.

The rule is a major change in U.S. asylum law. It denies asylum protection to most migrants arriving at the Southern border unless they first apply in a country they passed through on the way.

Good news came out from the Centers for Disease Control and Prevention Wednesday: Preliminary data shows reported drug overdoses declined 4.2% in 2018, after rising precipitously for decades.

Updated at 10:30 p.m. ET

A U.S. Navy warship called the USS Boxer took down an Iranian drone in the Strait of Hormuz on Thursday, President Trump said, adding, "The drone was immediately destroyed."

"The Boxer took defensive action against an Iranian drone," Trump said, giving details about the encounter at the start of a flag presentation ceremony at the White House. He said the drone had closed to about 1,000 yards from the U.S. ship, "ignoring multiple calls to stand down."

Most days, 25-year-old Chavonne can push her student loan debt to the back of her mind.

Between short-term office jobs in the Washington, D.C., area, she drives for Uber. But once in awhile, a debt collector will get hold of her cellphone number — the one she keeps changing to avoid them — and it all comes back fresh. "I'll be like, 'Oh no!' " she says. "It's a sad reminder that I owe somebody money!"

In April, she got another reminder when the government seized her tax return.

All this for a degree she never finished.

Researchers are prescribing exercise as if it were a drug in a study that aims to see if it can prevent Alzheimer's disease.

"We are testing if exercise is medicine for people with a mild memory problem," says Laura Baker, principal investigator of the nationwide EXERT study and associate director of the Alzheimer's Disease Research Center at Wake Forest School of Medicine.