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Good morning.
Here’s what you need to know:

• Britain faces an agonizing decision: How should it model its future ties with the European Union?
Some think the country should be like Norway, outside the E.U. but tightly bound to the bloc’s high social and economic standards. Others want the country to break free, cut taxes and regulations and transform itself into a European version of Singapore.
The stakes are high for Britain’s economy. Brexit plans have already prompted thousands of Europeans to return to the Continent, forcing British employers to compete for a diminishing pool of workers.
Theresa May, above, is expected to address the House of Commons on Monday over new trade deals.
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• Russia’s president, Vladimir V. Putin, called President Trump on Sunday to thank him for the C.I.A.’s help in disrupting an Islamic State attack in St. Petersburg.
In rare words of praise for the C.I.A., Mr. Putin said the agency had provided information that “helped detain terrorists planning explosions.”
Continue reading the main storyMeanwhile, in Washington, a lawyer for Mr. Trump accused Robert Mueller, the special counsel looking into Russian interference in U.S. elections, of illegally obtaining Trump transition emails, the latest in the mounting attacks on the investigation into Russian election meddling.
Above, Mr. Putin and Mr. Trump at a summit in Vietnam, in November.
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• The lights went out at the world’s busiest airport.
Passengers from around the world were stranded at Hartsfield-Jackson Atlanta International Airport after a power failure on Sunday. Many were held on the tarmac for hours without explanation.
Expect snarls to ripple through the air traffic system.
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• A Times investigation has brought to light a shadowy Pentagon program — parts of it remain classified — that since 2007 has investigated reports of unidentified flying objects.
One fighter pilot told us about a strange encounter in 2004 with a whitish, oval U.F.O. that “accelerated like nothing I’ve ever seen,” and left him “pretty weirded out.”
In less surprising political news, President Trump expects to sign the Republican tax bill this week. He has called it a Christmas present for the entire nation, but the fine print reveals some will get nicer gifts than others.
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“An economic agent on behalf of North Korea.”
The Australian federal police said Chan Han Choi, a naturalized citizen living in Sydney, had been arrested on charges of trying to help North Korea sell its missile parts and other military technology to “international entities.”
North Korea has been accelerating its nuclear and missile tests. Here’s what we know about the scientists, above, who serve the country’s leader, Kim Jong-un.
Last week, Secretary of State Rex W. Tillerson offered tantalizing details about how the U.S. would race inside North Korea to seize its nuclear weapons in the event of a collapse.
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• A $500 million yacht, a $450 million Leonardo da Vinci painting and the $300 million chateau above.
These are among the impulse buys of Crown Prince Mohammed bin Salman, the heir to the Saudi throne, who happens to be preaching fiscal austerity and leading a crackdown on corruption.
The purchase of Chateau Louis XIV “is a severe blow to that image,” one analyst said. [Lire en français.]
Business

• “The Last Jedi” made the jump to box office hyperspace, selling $450 million in tickets worldwide on its opening weekend.
The film’s stars — including, above, Daisy Ridley, Adam Driver and Mark Hamill — recently discussed new relationships, the joys of villainy and those porgs with our reporter.
• Uber secretly spied on key executives, drivers and employees at rival ride-hailing firms in multiple countries, according to a letter made public in a U.S. federal court.
• The computer chip industry is being shaken up by an aggressive set of chief executives who are pushing big acquisitions, slashing costs and driving up profits.
• Here’s a snapshot of global markets.
In the News

• In South Africa, disputes are delaying the vote to elect a leader to succeed President Jacob Zuma, whose administration has been plagued with scandals. [The New York Times]
• In Italy, unlike in the United States, accusations of sexual harassment and assault have been met with a collective “meh.” [The New York Times]
• Protesters booed and shouted “Shame” as European far-right leaders gathered at a weekend meeting in Prague to unify their stance on immigration and other issues. [The New York Times]
• In Pakistan, the Islamic State claimed responsibility for an assault on a church in Quetta that left at least eight dead and 30 injured, raising concerns about the security of the country’s Christians. [The New York Times]
• A French sailor circumnavigated the globe in 42 days and 16 hours, beating the previous world record by more than six days. [BBC]
Smarter Living
Tips, both new and old, for a more fulfilling life.

• Attention holiday travelers: Here are 10 places around the world that really know how to celebrate Christmas, including Prague, Zurich and Copenhagen.
• What to cook this week: Our food editor, Sam Sifton, suggests chicken adobo, Russian honey cake and more.
Noteworthy

• For five months, The New York Times tracked 21 public hospitals in Venezuela, where doctors are seeing record numbers of children with severe malnutrition. Hundreds have died.
• John Rutter’s carols are sung across the English-speaking world, but their tuneful accessibility has kept him from a place in the pantheon of serious composers.
• In memoriam: Marina Popovich, a test pilot who broke more than 100 flying records and was the first Soviet woman to break the sound barrier; and Aline Griffith, a former model from New York who transformed herself into a dressed-to-kill, self-proclaimed spy and Spanish countess.
• And our pop critics collected notable new music, including Lin-Manuel Miranda’s collaboration with the Decemberists and a Thelonious Monk reissue.
Back Story

On Dec. 18, 1941, less than two weeks after the attack on Pearl Harbor, the Sunday editor for The Times sent a memo to the publisher, Arthur Hays Sulzberger.
It said: “We ought to proceed with the puzzle, especially in view of the fact it is possible there will now be bleak blackout hours — or if not that then certainly a need for relaxation of some kind or other.”
That’s how a time of national grief helped lead to one of The Times’s most joyful and beloved features. The crossword puzzle debuted some two months later as a weekly feature in the Sunday magazine.
The editor at the time, Margaret Farrar, followed a simple rule: good manners. She refused to allow unpleasant or impolite language — a rule that’s still followed by The Times’s current crossword editor, Will Shortz.
Nowadays, we like to think of our crossword puzzle as the form’s gold standard.
But The Times didn’t always hold crosswords in high regard. In 1924, a Times opinion column called the completion of crosswords a “sinful waste.”
Crossword solvers, the column claimed, “get nothing out of it except a primitive sort of mental exercise.”
Many of us would disagree.
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