After launching its third intercontinental ballistic missile of the year, North Korea declared that it had achieved its long-held goal of becoming a full nuclear power. Its provocative actions throughout the year sharply raised the stakes of its rivalry with the United States, a dispute compounded by a series of taunts and insults between President Donald Trump and North Korea's leader, Kim Jong Un. Kim called Trump a "dotard," while Trump referred to Kim as "Little Rocket Man" and threatened to rain "fire and fury" on Pyongyang.

Two major European governments got a taste of populist resurgence. In May, Emmanuel Macron – a centrist who shunned his country's establishment parties – became France's youngest president by defeating the far-right nationalist Marine Le Pen. In September, Germany's Angela Merkel weathered a strong nationalist challenge to win a parliamentary election – but with such a weak mandate that she referred to herself as a "caretaker chancellor" and was considering another election.

The singer Ariana Grande had just ended her concert in Manchester, England, when a suicide bomber struck. Twenty-two people died and dozens more were injured in the May 22 attack, claimed by Islamic State. It was one of several terrorist strikes in the United Kingdom for which Islamic State took responsibility in 2017, including attacks outside Parliament in March, at London Bridge in June, and on the London Underground in September. In an apparent revenge attack in June, a man from Wales drove his car into a crowd of Muslim worshipers in London.

Islamic State lost its caliphate. After months of block-by-block fighting, U.S.-backed Iraqi forces reclaimed Iraq's second-largest city, Mosul, in July. In October, U.S.-backed forces in Syria wrested control of the group's "capital," Raqqa. After those defeats, the Islamist extremists were left with very little territory, but experts warned that they still had the capability to carry out and inspire international terrorism.

A year ago, few people outside Myanmar and its neighboring countries had heard of Rohingya Muslims, although their plight had been worsening steadily in recent years. In August, Rohingya began fleeing Rakhine state in Myanmar as government troops carried out what the United Nations called "a textbook example of ethnic cleansing" in response to an insurgent attack. First thousands, then tens of thousands, then hundreds of thousands fled, mostly to Bangladesh. The crisis tarnished the international reputation of Myanmar's leader, Aung San Suu Kyi.

Sirens sounded at 11 a.m. Sept. 20, marking the 32nd anniversary of one of Mexico's worst disasters, a magnitude 8.0 earthquake in which thousands died in the nation's capital. About two hours after the observance, it happened again. This time, the quake was magnitude 7.1, also centered near Mexico City. Lessons learned in the previous earthquake helped reduce the death toll to about 325. The quake also led to a surge of national pride as Mexicans came together and helped each other.

Until 2017, only one Chinese leader – Mao Zedong – warranted a mention in the country's constitution while he was still alive and in power. That changed Oct. 24, when China's Communist Party agreed to insert Xi Jinping's name and ideology into the constitution. By the time his second five-year term was rubber-stamped at the Communist Party Congress, Xi had made his mark as the country's strongest, most authoritarian leader since Mao, with no clear successor in sight.

With nationalism spreading in Europe, it was perhaps inevitable that separatist movements could grow. So it was in Spain, where the affluent northeastern province of Catalonia – which has long nurtured its own identity and language – voted overwhelmingly Oct. 1 to declare independence. What followed was a high-stakes game of chicken between the Spanish government and Catalan leaders – who fled to Belgium to escape arrest. For now, Catalonia remains part of Spain.

He had been president for 37 years, a revolutionary figure who helped end white minority rule in Zimbabwe, the former Rhodesia. Most people in his country could remember no other leader. All that came to an abrupt and surprising end Nov. 21 when Robert Mugabe, a hero who became a dictator, resigned in the face of a de facto coup by his military.