'Start Here': Trump wades into Brexit crisis ahead of visit, and officials search for motive in Virginia Beach massacre

It's Monday, June 3, 2019. Let's start here.

1. 'About to get very small'

President Donald Trump waded into the Brexit crisis before taking off to London for an official visit beginning today.

In an interview with The Sun newspaper, he backed Boris Johnson, the former British foreign secretary and Brexit campaigner, to replace Theresa May as prime minister. Trump also suggested to the Sunday Times that the U.K. should "walk away" from negotiations with the European Union if the government is unable to reach a favorable deal: "If you don't get the deal you want, if you don't get a fair deal, then you walk away."

Despite protests in London planned for Trump's arrival, ABC News' Terry Moran says on "Start Here" that the U.K. needs the U.S. and the president,now more than ever "for trade deals, for remaining a part of the big conversations around the world, because they're about to get very small."

Trump also stirred controversy with comments this weekend about Meghan Markle, the beloved Duchess of Sussex, but he denied reports that he called her "nasty" when a reporter told him that she'd criticized him. When an audio recording of Trump using the word "nasty" in connection with Markle surfaced, a White House official told ABC News that it was taken out of context.

2. 'Chasing the sounds of gunshots'

Law enforcement officials in Virginia Beach have unveiled a timeline of what happened inside a municipal building where a gunman opened fire on Friday, killing 12 before he was shot dead by police.

"It's a sprawling building -- officers described it as a honeycomb-type building, a maze of hallways and different offices," ABC News' Whit Johnson says from Virginia Beach. "Once the officers get inside, there's screaming, they're stepping over bleeding victims, they're chasing the sounds of gunshots to try to find this gunman."

Virginia Beach Police Chief James Cervera said it took officers 36 minutes from the time the first 911 call came in to engage suspected shooter DeWayne Craddock, render him aid and transport him to the hospital, where he later died. Four other people remained in critical condition as of Sunday night.

Authorities are still trying to determine a motive.

3. 'Maximum pressure'

Tensions continue mounting between the U.S. and Iran amid a "maximum pressure" campaign by the Trump administration to force Iran to restart nuclear negotiations.

But despite sanctions and economic distress, Iran is holding firm, Iranian Foreign Minister Javad Zarif told ABC News Chief Global Affairs Correspondent Martha Raddatz in an exclusive interview.

"This may work in a real estate market. It does not work in dealing with Iran," he said. "It may work even with in dealing with other countries, for a brief period, not for long term, but it doesn't work with Iran for a brief period, or in medium or long."

Iranians meanwhile are caught in the middle of the standoff, Raddatz says on today's podcast: "I was here four years ago, the night they announced that the nuclear deal had been agreed upon, and there was jubilation in the streets. ... Now they're back where they started and really feeling it."

"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.

Elsewhere:

'People of interest are also being questioned in relation to some of our incidents and detectives have good video leads in others': At least 10 people are shot to death in Chicago over the weekend.

'Leaving shortly': The chairman of Trump's Council of Economic Advisers will be resigning.

'I know he will retaliate by trying to harm me in some way': The estranged husband of a missing Connecticut woman and his girlfriend are arrested.

From our friends at FiveThirtyEight:

What bills get passed in states where parties share power?: The 22 totally GOP-controlled states have focused on issues like limiting abortion access, making guns more accessible and banning so-called sanctuary cities. The 14 states where Democrats have a state-government "trifecta" have pursued goals like increasing the minimum wage, reducing or totally eliminating penalties for marijuana use and creating programs to make college more affordable. So what's happening in the 14 other states -- the ones where the two parties share power?

Doff your cap:

Model Winnie Harlow celebrated her first Vogue cover in a big way.

The 24-year-old beauty struck a pose on the June cover of Vogue Arabia and expressed her gratitude in an Instagram post.

"Every night traveling and living alone without my family and friends," she wrote. "All to be able to tell.. no SHOW the world that representation matters."

"That beauty is within the eye of the beholder," she added, "and no ones 'definition of beauty' should matter but your own."