Charlotte Heffelmire, 15, of McLean is using helium balloons and neighborhood donations to break into North Korea.

Standing on the roof of a building in South Korea, Heffelmire released about a dozen balloons — pearly greens, pinks and blues — that she hopes will float over the 2.5-mile-wide Korean Demilitarized Zone into North Korea.

“I sent about 1,000 balloons [over], about a dozen each release. We tie a dollar [a South Korean 1,000 won note] to each balloon and attach a note that reads ‘Stay Strong,’ in Korean,” said the teen, whose mother is Korean. She is planning her ninth visit to South Korea for the release of more balloons this month.

So far, Heffelmire estimates she has sent $2,500 tied to balloons over the DMZ. Her charity, Winds of Change, has raised about $14,000 toward the effort through Heffelmire seeking donations from family and friends and mowing yards to raise money. Her parents pay for her travel expenditures.

Heffelmire began the project about two years ago, releasing $400 tied to 400 balloons. Although the South Korean won is not the official currency of North Korea, Charlotte said she hopes there are markets in the north that will accept the funds.

“Whenever I think about North Korea, I think, ‘It needs to be changed.’ And [North Korea] can’t control the wind,” said Heffelmire, explaining the name of her charity.

“I got the idea after watching this documentary from National Geographic where they were showing all these awful things going on in North Korea,” Heffelmire said. “These teens they were showing were so small from being malnourished that they looked like little kids.”

Heffelmire, a rising sophomore, attended the Madeira School last year.

“She’s Korean, not half. She’s always told me she’s 100 percent Korean,” said Heffelmire’s mother, Darmie Yoon, who emigrated from South Korea to the United States in 1985 for college. “When I lived in South Korea, I got a flier from North Korea. You would sometimes see them in the mountains. These fliers, I thought, had to come from a balloon. . . . There were fliers that would say their Korea or military was better than ours.”

As a child growing up in South Korea, Yoon said she was taught that North Korean children were not given the same advantages or quality of education as their South Korean peers. This is a lesson Yoon and her husband, Eric Heffelmire, shared with their children.

“Charlotte has grown up in two worlds — one cultural foot in America and the other in Korea — and has tried to take the best out of both cultures,” Eric Heffelmire said. “Because she is part Korean, I think she feels for the sick and dying North Korean children more and at a deeper emotional level than she might otherwise.”

The 160-mile-long DMZ is considered by the U.S. Department of State to be the most heavily militarized border in the world and divides the Korean Peninsula.

Because of the nature of the DMZ, Charlotte Heffelmire said balloons were a natural fit.

“I think her idea is very novel and a very brave thing for her to do as someone her age,” said family friend and teacher Jessica Kim, who was born in South Korea. “I think it’s a small thing that many people may not recognize, but the small things all add up.”

Kim, who came to the United States in the 1980s, said children of Korean Americans sometimes do not make or feel the connection with North Korea.

“The way North Korea and South Korea see each other hasn’t changed a lot,” Kim said. “My parents lived through the Korean War and moved down to the South.”

She said many South Koreans share the view that there is an opportunity to unite the Korean Peninsula, but there are concerns about what that could mean.

“They are eager to be united, but they also want to be protected,” Kim said, adding that charities such as Heffelmire’s can help break barriers.

Heffelmire said she is not sure how successful her efforts are and, because of the lack of communication with North Korea, she might never find out.

“Even if these balloons don’t actually get there, there’s hope in that we’re helping or doing something,” Heffelmire said. “You’ve seen pictures and videos, but you can’t fully understand what is being done to these people by their own government. . . . Be grateful for what you have.”

While Winds of Change is gearing up for its next balloon launch, Heffelmire is expanding her venture to include reading glasses. Eric Heffelmire said many North Korean children need eyeglasses, which are not available or unaffordable.

Charlotte Heffelmire is experimenting with the idea of tying eyeglasses to balloons and launching them along with the money and note across the DMZ.

Donations of eyeglasses or money can be sent to Charlotte Heffelmire, Winds of Change, 9540 Noory Ct., Vienna, Va. 22182.