GANGHWA ISLAND, South Korea — The water bottles, filled with rice and worm medicine and ointment and USB sticks containing movies and songs and President Trump’s State of the Union address, were carried away by the currents. Their destination: North Korea.

Twice a month when the tides are right, activists led by Jung Gwang-il, a former North Korean political prisoner turned human rights advocate, toss hundreds of bottles into the Han River to be carried downstream in the hope that some will end up in the hands of North Koreans, who are hungry for both food and information.

“I want people in North Korea to know that even the president of the United States is concerned about human rights,” Jung said as he prepared to cast 400 more bottles into the river. “I want to encourage them to stay the course against the North Korean regime.” 

The USB sticks in these bottles contained subtitled footage of Trump’s January address, in which the president called North Korea’s dictatorship “cruel” and “depraved.”

Jung, who met Trump in the Oval Office in January and has a picture of the two of them together in his South Korean messaging app profile, supports the president’s “maximum pressure” approach to dealing with Kim Jong Un. 

South Korean activists hope floating bottles containing items banned in North Korea will find their way into the hands of regular citizens. (Anna Fifield, Jason Aldag/The Washington Post)

Through his organization, No Chain for North Korea, he’s trying to apply his own form of pressure on the Kim regime by breaking the information blockade.

Besides Trump’s address, the USB sticks also hold YouTube videos showing what life is like for young people in the United States, as well as the movies “The Wall,” an Irish movie about a North Korean poet, and “The Interview,” the comedy about assassinating Kim that is believed to have led North Korean hackers to attack Sony Pictures in 2014.

Jung also loaded footage of a North Korean musical group’s performance in Seoul in February — to show that they were performing songs that are banned in the North — and the performance that South Korean singers gave in Pyongyang last month. Both were heavily censored in the North.

North Korea’s Kim family has remained in power for seven decades partly by shutting off all information from the outside world, instead telling the impoverished and oppressed citizens that they live in a socialist paradise.

But as information has seeped in via radio waves, cellphones and USB sticks, more and more people have come to realize that this is a lie.

Thae Yong Ho, who was North Korea’s deputy ambassador in London until his escape in 2016, says that getting information into the country is crucial to counteracting the state’s propaganda.

“We should educate the North Korean people so that they can have their own ‘Korean Spring,’ ” he told The Washington Post last year. 

Dealing in outside media has become big business in North Korea, with merchants in the markets selling USB drives that can be inserted into TVs or DVD players, and micro-SD cards that can be put into phones.

A 2015 survey of people who had escaped from North Korea found that 81 percent had watched foreign media on USB drives while in the country.

Jung and other activists have, over recent years, become increasingly ingenious at getting information into the country. Some set up radio stations in which escapees from North Korea talk about their lives in the South. Some fly huge balloons filled with brochures and media across the border from South Korea when the winds are right. Others smuggle bags of DVDs over the border from China.

Jung tried drone delivery at one point, but that was tricky. So he went low-tech, relying on the river currents to wash bottles of information ashore.

Jung doesn’t have proof that North Koreans watch the movies or eat the rice he sends, but the Marine Corps has told him that they’ve seen people and boats collecting the bottles.

On a recent day, as the government in Seoul was preparing to host a summit between South Korean President Moon Jae-in and Kim, Jung and his team headed out to a secluded spot on the banks of the Han.

His work is sensitive — and not just because the North Korean regime objects to it. The South Korean government is concerned that such activities might antagonize the regime at a time when it’s trying to make diplomatic progress.

No Chain gets no government funding, relying instead on donations. The Human Rights Foundation, a New York-based nonprofit group, donates drives as part of its “Flashdrives for Freedom” project, which aims to penetrate isolated places.

Student groups at Yale and the University of Alabama have donated USB drives, as has a high school in Wyoming. Sometimes individual donors in the United States and South Korea send old ones, too.

The three pounds of rice in each bottle, donated by South Korean churches, is worth about two months’ salary for a state worker in North Korea.

Lee Hae-kyung, who worked as a pharmacist at a hospital in North Korea, had come to the river bank bringing with him antiseptic ointment and tablets to counteract parasites — like the ones that riddled the soldier who escaped across the border to the South last year.

When she lived in North Korea, she said, people were told that such supplies from the South were poisoned. “But now North Korean people know that it’s not.” 

“Change doesn’t happen when people are hungry,” said Lee Soon-shil, who escaped from North Korea a decade ago. “So when they find these bottles, they can cure their hunger and learn about South Korea at the same time. I think the USBs are going to be a bigger help than the rice itself.” 

With the bottles all ready and noon approaching — the best time to hit the right currents — the activists and several dozen members of a church group that had donated the rice gathered on the rocks overlooking the Han. 

They prayed loudly together. “Lord, please work for us,” they chanted. Then they started flinging the bottles into the water.

“People in North Korea will be swarming around these at dawn tomorrow,” said Kim Yong-hwa, the chairman of the North Korean Refugees Human Rights Association, another group involved in the effort.

While Moon was talking about guaranteeing the future of the North Korean regime as part of the effort to persuade Pyongyang to give up its nuclear weapons, the activists were trying to care for the North Korean people by feeding and educating them, Kim said.

That could pay different security dividends, he said. “We think that the people who receive this rice are going to be on our side. They’re not going to want to attack us.” 

The currents carried the bottles away, to drift possibly as far as 25 miles. Whether they arrived, the activists didn’t know. But they had to try.

Min Joo Kim contributed to this report.