A silent flip of the collar. A subtle twirl of the hem. If a safety pin was underneath, that person was a friend.

When the Germans occupied Northwestern Europe during World War II, Dutch and Norwegian citizens communicated their national solidarity with tiny devices: safety pins or paper clips. It was inexpensive and universally portable. The trick was keeping it hidden.

In 2016, people are wearing safety pins for different reasons.

Since Britons voted to withdraw from the European Union in June, xenophobic abuse against immigrants and people of color has risen by more than 50%. Soon after the referendum, a concerned citizen identified only as Allison (@cheeah on Twitter) tweeted about a plan to support those targeted by racism. She would wear a safety pin to show people she was an ally, that she would help intervene in instances of antagonism.

The call to action went viral. People tweeted photos of their own safety pins along with pledges to stand with victims.

After GOP nominee Donald Trump was elected US president, Americans also took up the safety pins. During the campaign, Trump promised to deport undocumented immigrants, ban Muslims from the country, and build a wall on the Mexican border. He called Mexicans “rapists” and criminals and, in a leaked tape from 2005, boasted of “grabbing” women “by the the pussy.” As a result, Trump’s election has terrified millions of Americans whose ethnicity, gender, sexual orientation, or disabilities render them targets for violence. As in the UK, allies wore safety pins as a visual reassurance to frightened groups of people: “We stand by you. We will help protect you. We are your friends.”

The Netherlands was neutral at the outset of World War II, but Germany invaded on May 10, 1940, in part to weaken British forces in mainland Europe by drawing them further toward Belgium.

The Dutch army initially managed to defend against the German advance, despite using minimal and mostly antique weaponry left over from World War I. When a parachute assault aimed to capture the Dutch royal family and the government at The Hague, Dutch forces fought back. German military were killed, wounded, or captured in the thousands. Meanwhile, the Germans struck Rotterdam and killed roughly 900 civilians.

The Netherlands knew it wouldn’t be able to sustain a defense before British and French troops could arrive. The country surrendered on May 15. But Dutch citizens came together under occupied watch. In a 1941 British war film titled One of Our Aircraft Is Down, resistors were depicted wearing safety pins under their collars or hems, flashing them to other trusted underground confederates. The implicit message: “Keep together. Keep your mouth shut.”

In reality, the Dutch may have never used safety pins. But the Norwegians most definitely had their own version of the symbology. In autumn 1940, students at Oslo University began wearing paperclips on their lapels or as bracelets to signify unity, as a clip binds papers together.

Though she escaped, Dutch Queen Wilhelmina inspired resistance efforts; her photo was used as another sign of resistance against German occupation. Underground newspapers sprang up to counterbalance Nazi propaganda, as did a sophisticated operation for forging ration cards and money, and an information network to communicate internally and with British intelligence. Many Dutch people hid Jews, and others spied from positions in the police force or occupied government.

These acts of resistance were incredibly dangerous. People were punished, imprisoned, sent to concentration camps, or even killed. But even small shows of defiance, like office supplies, inspired hope.

Clarification: This article was changed to reflect that safety pins worn as a symbol of resistance in the Netherlands was a notion made popular by the British One of Our Aircraft is Missing (1941).