Good morning, NBC News readers.

Record-breaking flooding is wreaking havoc across the Midwest — including forcing the U.S. Strategic Command in Nebraska to sharply scale back operations.

Here's what we're watching today.

Midwest flooding forces hundreds from their homes

Heavy rain and snowmelt have led to dangerously high water in several states across the Midwest, including Nebraska, Iowa and Wisconsin.

Hundreds of families have been forced to flee their homes and at least three deaths were blamed on what the National Weather Service called "major and historical river flooding" along parts of the Missouri and Mississippi river basins.

U.S. Strategic Command, which oversees the U.S. nuclear forces from Offutt Air Force Base near Omaha, said Sunday that floodwaters had overwhelmed the southeastern side of the base and ordered all but "mission critical personnel" to stay home on Sunday.

'We made a heart for you. 50 hearts for 50 lives'

Thousands of people paid tribute Sunday at makeshift memorials to the 50 people slain by a gunman at two mosques in Christchurch, New Zealand.

Hundreds of flowers were piled up amid candles, balloons and notes of grief and love outside the Al Noor mosque and the city's botanical gardens.

Days after Friday's attack, relatives were still waiting for authorities to release the bodies. Islamic law calls for bodies to be cleansed and buried as soon as possible after death, usually within 24 hours.

Police Commissioner Mike Bush said that authorities are aware of the cultural and religious needs and that they are working as "quickly and as sensitively as possible."

Prime Minister Jacinda Ardern hugs a mourner at the Kilbirnie Mosque in Wellington, New Zealand, on Sunday. Hagen Hopkins / Getty Images

Mulvaney: Trump is 'not a white supremacist'

Acting White House chief of staff Mick Mulvaney defended his boss on Sunday after President Donald Trump appeared to downplay the threat of white nationalists.

Trump condemned the mosque attacks as a "horrible, horrible thing" on Friday. But when he was asked if he thought white nationalism was a rising threat, Trump replied: “I think it’s a small group of people that have very, very serious problems."

The president's statement contradicts the warnings of his own administration.

The FBI and the Department of Homeland Security warned in a 2017 intelligence bulletin that white supremacist groups had carried out more attacks in the U.S. than any other domestic extremist group over the past 16 years. And officials believe they are likely to carry out more.

Did you miss Meet the Press yesterday? Watch the highlights of the show in about one minute below. Chuck Todd hit the campaign trail in Iowa and talked to presidential contenders Beto O’Rourke and Sen. Amy Klobuchar.

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One fun thing

Willie Geist sat down with Academy Award-nominated actor Woody Harrelson to talk about his 35-year career in Hollywood — from his time in “Cheers” to the premiere of his latest movie, “The Highwaymen.”

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Thanks, Petra