Good morning, NBC News readers.

President Donald Trump officially kicked off his 2020 re-election campaign with a dire warning, we have more on Patrick Shanahan's abrupt exit from the Pentagon and meet some of the nurses who cared for AIDS patients when no one else would.

Here's what we're watching today.

Trump kicks off 2020 'Keep America Great' campaign

"Our radical Democrat opponents are driven by hatred, prejudice and rage," President Donald Trump said as he officially kicked off his re-election campaign at a packed rally in Orlando, Florida, on Tuesday night. "They want to destroy you and they want to destroy our country as we know it."

The president stuck to a string of familiar chants — "build the wall," "CNN sucks" and "lock her up" among them — as he aims a message directly at his base ahead of 2020.

U.N. report finds 'credible evidence' Saudi crown prince could be liable for Khashoggi killing

The United Nations extrajudicial executions investigator is recommending an investigation into the possible role of Saudi Crown Prince Mohammad bin Salman in the killing of Washington Post journalist Jamal Khashoggi.

In a 101-page report into the journalist's murder at the Saudi consulate in Istanbul last October, Agnes Callamard called on U.N. bodies or the U.N. Secretary-General Antonio Guterres to "demand" a follow-up criminal investigation.

"No conclusion is made as to guilt," she wrote. "The only conclusion made is that there is credible evidence meriting further investigation."

Four face charges in rocket attack that killed 298 in jet crash

An international team of investigators have identified four people they say were responsible for the rocket attack that downed Malaysia Airlines flight MH17 over eastern Ukraine in 2014, killing 298 people.

The four suspects include three Russian nationals and one Ukrainian.

Shanahan withdraws from consideration for Pentagon chief

Patrick Shanahan, the acting secretary of defense who Trump said would be tapped to take over the job permanently, abruptly stepped down and withdrew himself from consideration for the Cabinet position on Tuesday.

The announcement came within minutes of a report published in The Washington Post that outlined a series of alleged domestic violence incidents within Shanahan's family.

His sudden departure raises questions about vetting within the Trump administration. And leaves the Pentagon in a state of upheaval amid increased tensions with Iran.

The president announced that Secretary of the Army Mark Esper, a former Raytheon executive, will take Shanahan's place as acting defense secretary.

No, the Dominican Republic hasn't suddenly become more dangerous

Despite a rash of news stories about mysterious deaths on the small Caribbean island, statistics indicate you're more likely to die as an American in the United States than you are as an American in the Dominican Republic.

In general terms, nothing unusual is going on in the Dominican Republic

"We have not seen an uptick in the number of U.S. citizen deaths reported to the department," a State Department official told NBC News on Tuesday.

That should be ice...

Sled dogs wade through ankle-deep water on top of a melting ice sheet in North Western Greenland in a photo taken by Steffen Olsen, a climate scientist at the Danish Meteorological Institute, on June 13. Steffen Olsen / AFP - Getty Images

The image above has gone viral as an example of rising temperatures and climate change.

While the stunning photo has global implications, Olsen noted in his original tweet that the rising temperatures have a direct impact on locals. “Communities in #Greenland rely on the sea ice for transport, hunting and fishing.”

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Plus

Teen was charged with friend's murder after man allegedly offered $9 million for video evidence of the crime.

Meet the nurses who cared for AIDS patients when no one else would.

Politicians hammer Facebook over Libra digital currency project.

THINK about it

Trump may have just walked himself into a post-presidential indictment, Jessica Levinson, professor at Loyola Law School, writes in an opinion piece.

Live BETTER

Studies show that what you wear can affect your performance. Mental game coach Todd Herman shares how the technique helped Martin Luther King, Jr. and Beyonce. And how it can help you, too.

Quote of the day

"Simply put, if we want to beat Donald Trump, we must put winning over political purity."

— Rep. Stephanie Murphy, D-Fla., a leader of the moderate Blue Dog Democrats

One fun thing

What's behind those hard-to-resist puppy dog eyes?

New research suggests that over thousands of years of dog domestication, people preferred pups that could pull off that appealing, sad look. And that encouraged the development of the facial muscle that creates it.

Today, pooches use the muscle to raise their eyebrows and make the babylike expression. That muscle is virtually absent in their ancestors, the wolves.

Thanks for reading the Morning Rundown.

If you have any comments — likes, dislikes — drop me an email at: petra@nbcuni.com

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Thanks, Petra