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KNOW IT ALL: Monday's Top Stories at NBC News

Here's a look at today's key headlines.
Charles Koch stands for a portrait after an interview with the Washington Post at the Freedom Partners Summit on Monday, August 3, 2015 in Dana Point, CA.Patrick T. Fallon / The Washington Post via Getty Images file

Good morning. Here are some of the stories we're following today:

1. Cruz and Kasich Team Up to Stop Trump

The campaigns of Ted Cruz and John Kasich announced an agreement Sunday night to coordinate their efforts to prevent Donald Trump from winning the GOP's presidential nomination before the Republican National Convention. Only Cruz will compete against Trump in Indiana and Kasich will turn his attention to Oregon and New Mexico. Trump responded late Sunday, tweeting that "Lyin' Ted" and Kasich were "colluding" against him. Read more in POLITICS.

2. U.S. to Send More Military Personnel to Syria

President Barack Obama said the U.S. will send an additional 250 military personnel to Syria, significantly expanding the American presence there to fight ISIS. Obama made the announcement in a speech in Germany. He said the additional troops — including some special forces — were necessary in order to "keep up this momentum" against ISIS. Read more in NEWS.

3. Marijuana 'Operations' Found at Scenes of Ohio Family Executions

Marijuana "grow operations" were found at three of the four scenes where eight members of an Ohio family were found murdered "execution style" Friday, authorities said. Ohio Attorney General Mike DeWine said the killings of the victims — all members of the Rhoden family of Piketon — were a "pre-planned execution." The killer or killers are still on the loose, and authorities on Sunday wouldn't say whether they had identified any suspects. Read more in NEWS.

4. Koch: ‘Possible’ Clinton Would Be Better Than GOP Rivals

Conservative billionaire Charles Koch said in an interview that aired Sunday that Hillary Clinton could possibly be preferable to a Republican for president. “We would have to believe her actions would be quite different than her rhetoric. Let me put it that way,” Koch said. Clinton said in a tweet Sunday that she wasn't "interested in endorsements from people who deny climate science and try to make it harder for people to vote." Read more in POLITICS.

5. Obama Responds to N. Korea's Promise to Halt Nuke Program

President Obama said Sunday that he doesn't take seriously North Korea's claim that it would halt nuclear tests if the U.S. suspends military exercises with South Korea. North Korea's Foreign Minister Ri Su Yong made the ultimatum in an exclusive interview with The Associated Press on Saturday, hours after North Korea test-fired a ballistic missile from a submarine. Obama said the U.S. would engage in "serious conversations" with North Korea only if the country shows that it is serious about ending its nuclear program. Read more in NEWS.

6. Rash of Severe Storms Promises Large Hail, Twisters

Dangerous storms packing large hail and potential tornadoes were bearing down on large swaths of the country on Monday, with forecasters warning of a bumpy week ahead. The Plains got an initial taste of the severe-weather outbreak on Sunday. Hail nearly twice the size of a quarter was spotted in Nebraska — along with what appeared to be tornadoes. Read more in WEATHER.

7. Police Chopper Stops Train From Crashing Into Car on Tracks

When the crew of a police helicopter saw a car on train tracks in Southern California, they acted quickly and cast a spotlight on the vehicle to alert the train conductor. The crew said they thought the train might still hit the car because of how long it takes for trains to come to a full stop, but the train ended up fully halting 40 feet before hitting the car. Read more at NBC Southern California.

Nightly Spotlight: Family, Friends Celebrate Prince

There were more tributes to Prince over the weekend as his family held a private memorial service for the music legend and announced that his remains had been cremated.