'Start Here': Tensions rise after Iran seizes British tanker, Puerto Rico governor will not seek reelection

Here's what you need to know to start your day.

It's Monday, July 22, 2019. Let's start here.

1. Tensions rising

"If you obey you will be safe."

Iranian officials said the British vessel violated international maritime laws. The U.K. claimed the incident was retaliation for the British seizure of an Iranian tanker off the coast of Gibraltar less than a month ago after officials said Iran violated European Union sanctions by trying to ship oil to Syria.

It's the latest escalation of tensions with Iran, which the U.S. and its allies are trying to navigate, according to ABC News' Elizabeth McLaughlin on "Start Here," "What's really key in what you're hearing from U.S. officials time and time again is how do we calm the tensions and how do we ensure the security of these transits in and out of the Strait of Hormuz."

2. Puerto Rico protests

Puerto Rico Gov. Ricardo Rossello said he will not seek reelection next year as nearly a million people are expected to take to the streets Monday, demanding his resignation.

Thousands of Puerto Ricans demonstrated outside of the governor's mansion over the weekend amid a firestorm over leaked offensive comments he made in a group chat with members of his inner circle, which included sexist and homophobic language as well as jokes about the victims of Hurricane Maria.

ABC News' Victor Oquendo was with protesters in the streets of San Juan as the governor made his announcement in a Facebook video on Sunday, "Those chants, 'Ricky renuncia,' Ricky resign, they built up once again. It didn't take long for me to find people on every corner saying it's simply not enough."

3. Boris and Brexit

The replacement for outgoing British Prime Minister Theresa May will take office on Wednesday as the U.K. is set to leave the European Union in just a few months.

Former British Foreign Secretary Boris Johnson is likely to be named as the next prime minister, according to ABC News Foreign Editor Marcus Wilford, and while the Brexit champion may be the Conservative Party's choice, he could face trouble from other members once he's in office.

"One of the first things that may happen once he's elected is that the rest of Parliament rallies against him and tries to bring him down with a general election," Wilford tells "Start Here."

4. 'Endgame' is the beginning

It was a big weekend for the Marvel Cinematic Universe: "Avengers: Endgame" surpassed "Avatar" to become the highest-grossing film of all time and a vast lineup of films and shows were announced at San Diego Comic-Con.

Between Marvel's first Asian superhero movie, "Shang-Chi," actress Natalie Portman as a female Thor, and Oscar-winner Mahershala Ali as the vampire hunter Blade, the studio is entering a new era of storytelling with diversity and representation, says Inverse Senior Entertainment Writer Eric Francisco.

"If you promise people that, 'Hey, they can see themselves as superheroes on the big screen,' of course people are going to shell out dollars and they're going to want to see these movies," he says.

Disney is the parent company of ABC News and Marvel Studios.

"Start Here," ABC News' flagship podcast, offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, iHeartRadio, Spotify, Stitcher, TuneIn or the ABC News app. Follow @StartHereABC on Twitter, Facebook and Instagram for exclusive content and show updates.


'When you hear the roar, go indoors': Eight people were injured in a lightning strike on a Florida beach on Sunday.

'Freak accident' tragedy: A father of six children died over the weekend when he broke his neck after being hit by a wave in North Carolina.

'Aggressively shadowed': While the focus has been on Iran-U.S. confrontations in the Middle East, the military released heart-stopping video of a Venezuelan fighter jet shadowing a U.S. plane in an act U.S. Southern Command called "unprofessional."

From our friends at FiveThirtyEight:

Bulletpoint: Beto O’Rourke Doesn’t Have A Base: There are plenty of young voters, white voters and moderate voters in the Democratic electorate. But there aren’t that many who are young and white and moderate.

Doff your cap:

OK, so sometimes it's easy to get a little tired of the British royal family. The "will they" and "won't they" of glorified celebrities, in a country the U.S. ditched 250 years ago, is easy to bash.

But then you see a picture of Prince George!

The eldest child of Prince Williams and Duchess Kate celebrates his 6th birthday today, and the palace shared some photos snapped by his mom. Or is that mum?