Tonight, the fallout after the group chat that exposed top American officials thinking

ahead of military strikes.

Top Democrats and Republicans demanding answers and calling for investigations as the White

House tries to downplay the significance.

The president standing by the National Security Advisor saying he's learned his lesson. But top intelligence officials

face intense questions about the leak, discussing plans to attack Houthi positions in Yemen, while

the top editor was in the text thread. So how did such a messy lapse occur? Serious concerns about

Social Security, the nominee for administrator grilled, as Elon Musk calls it a Ponzi scheme, can trillions in cuts be made without impacting payments to so many Americans.

Our exclusive, inside NATO's new deep sea mission to fend off Russia from slashing critical cables that carry power, data, and a lifeline

to Europe. Why officials in Costa Rica now say the son of former Yankee star Brett Gardner

didn't die of asphyxiation while on vacation. What more parents are considering doing for

their kids as measles cases rise.

Seeing red over dyes in food, the first state to ban more than seven of them

and why 20 more states aren't far behind.

And all the pretty horses, how actor Daryl Hannah and her miniature pals are making a big impression.

This is NBC Nightly News with Lester Holt.

Good evening and welcome. President Trump is downplaying the security breach that

inadvertently led a journalist in on a group text thread, where that reporter says imminent

military attack plans were discussed

among top administration officials.

The White House line echoed at a contentious Senate Intelligence Committee hearing today,

where the nation's top intelligence figures argued the chats were not classified,

...