NEW YORK (AP) – Soraya Santiago, one of Puerto Rico’s most prominent Puerto Rican rights activists, has died at age 73 after an 18-year battle with an aggressive form of breast cancer.

The New York-based American Friends Service Committee, where Santiago worked and reported to, said she died Sunday from complications related to lymphoma, according to medical records posted Tuesday on its website. She had no survivors.

Santiago was born in 1936 on Puerto Rico’s southern mainland. She later established career in Puerto Rican activism through community work, community leadership training and a watchdog role with her campaign group, the Defend Puerto Rico Network (DoREAP).

Her public service came in 2008 when she led a sit-in at the Federal Emergency Management Agency’s San Juan headquarters to show support for those displaced by Hurricane Maria and defend the federal government’s relief funds in the wake of the hurricane. She also condemned President Barack Obama for his refusal to attend the United Nations’ annual General Assembly.

Santiago was instrumental in building Puerto Rico’s international connections and promoting the country’s human rights.

President Donald Trump, who visited Puerto Rico on his first trip to the island in September 2017, tweeted Monday evening: “Soraya Santiago was an amazing woman and a great friend of ours on the island. She was very dedicated and fought very hard for the children of the island. God bless her.”

When the brutal 2013 civil war between the U.S. military and self-declared successor forces of dictator Francisco “Puerto Rico” Diaz de Campo ended, Santiago led the civil defense efforts for the island. She also led the long-term political-diplomatic solidarity of hundreds of thousands of Puerto Ricans, asking for public trust during the crisis.

Santiago spoke at the U.N. and at the Democratic National Convention. She gave speeches at the Democratic Convention in 2016.

In April, Santiago argued in an opinion piece for The New York Times that increased U.S. support for Puerto Rico and deeper relationships across the hemisphere were at odds with the country’s long-term national goal of being a “light on the island.”

“We must recognize that this gives Puerto Rico a unique opportunity to act like an island on the edge,” she wrote. “But we must recognize that all the model models that have served us over the years must be dismantled if we are to stay on the edge.”

Santiago’s interest in U.S. politics grew out of that personal engagement. She went to Puerto Rico to collect Hurricane Maria debris after Maria’s arrival in September 2017. Santiago kept returning as she fought to build renewed awareness of the problem.

“I thought that it would not be long before Puerto Rico would become a nation,” she told The Associated Press in July 2017. “I was devastated and also happy that a new life, a new organization and a new network of women existed.”

In 2016, Santiago challenged then-U.S. Sen. Bernie Sanders for an endorsement in the Democratic nomination for president.

In an interview this month with the Los Angeles Times, Santiago and co-founder Tara Parkes hinted at a desire to see Puerto Rico regain full U.S. sovereignty. “We’re not a treaty state,” Santiago said. “Our politics, our people, our culture and values are indigenous.”

The nation’s border with the U.S. mainland has been a focal point of both dispute and hope in Puerto Rico.

Santiago and Parkes wrote in their text the reach of their work was made possible by the “Spanish Revolution.”

“Our union and struggle were born from a desire to free Puerto Rico from the tyranny of American foreign policy,” they wrote. “They meant freedom of speech, freedom of education, freedom of religion, freedom of the press, freedom of assembly, freedom of association, freedom to reside, and freedom to travel. They were victories for the rights of the free — and we also won the rights of the oppressor.”