A prominent climate activist in Vietnam was detained on Wednesday in what human rights experts say is the latest case of the country's ruling Communist Party suppressing civil society. The arrest came weeks after dozens of environmental and human rights groups urged President Joe Biden and other world leaders to pressure Vietnam on its human rights practices before industrialized nations send the country billions of dollars to fight climate change and boost its economic development.

The United Nations says Hoang Thi Minh Hong, founder of the environmental group CHANGE VN, was arrested on charges of tax evasion. The UN says Hoang is the fifth high-profile climate activist in Vietnam who has been charged with tax evasion in the past two years. Human rights experts say the Vietnamese government is arbitrarily enforcing the law to target civil society groups.

Vietnam is in the middle of trying to finalize a deal for at least $15.5 billion in climate funding from industrialized countries and investors. A global coalition of 36 civil society groups recently called on backers of the funding program, known as the Just Energy Transition Partnership (JETP), to ensure activists in Vietnam have a hand in designing and monitoring how the deal is carried out.

Under those circumstances, Hoang's arrest is "a huge slap in the face for the international community," says Ben Swanton, a director at the human rights group The 88 Project. "It demonstrates that, contrary to its propaganda, the Vietnamese government does not respect human rights and does not want civil society to participate in the country's energy transition."

Hoang was one of 12 people chosen from around the world in 2018 to study at Columbia University as an Obama Foundation Scholar. The foundation said she was selected for her work promoting "environmental preservation through communication, education, and community organizing toward a vision of a green and clean Vietnam protected by all people."

Vietnam's embassy in Washington didn't respond to messages seeking comment.

The State Department said in a statement that it's troubled by Hoang's arrest. "These detentions by Vietnamese authorities are part of a concerning pattern of arrests of local environmental and civil society advocates," a spokesperson said. "We also reiterate the vital importance of civil society partners like CHANGE in tackling global challenges, advancing sustainable prosperity in the global fight against climate change, and combating wildlife and timber trafficking."

The UN said Vietnam should release all prisoners it's detained arbitrarily and ensure that the country is complying with international human rights standards.

What's happening in Vietnam is part of a "larger pattern" of climate activists around the world facing retaliation for their work, says Maureen Harris, a senior advisor at the environmental group International Rivers.

"Often, the success of climate action has come down to the ability to actually set real targets, has come down to concerted pushes from grassroots movements," Harris says. "And as part of that, it's no coincidence that there's often a backlash against these voices who are sort of pushing the envelope on what they want to see achieved."

Vietnam was offered money through the JETP program after climate activists pushed the government to commit to eliminating or offsetting the country's carbon dioxide emissions by midcentury. But by the time the JETP was announced, activists whose campaigning paved for the climate deal were imprisoned in Vietnam on what critics say were trumped-up tax charges.

A UN working group recently said the treatment of one of those activists, Dang Dinh Bach, is a violation of international law.

Phil Robertson, deputy director of the Asia Division at Human Rights Watch, said in an email to NPR on Thursday that Hoang's arrest is part of a sweeping crackdown on environmental groups in Vietnam. He said that any criticism has come to be seen as seditious by the general secretary of the Communist Party of Vietnam, Nguyen Phu Trong, and that prominent environmental activists like Hoang aren't safe.

"The muted response by the U.S. and other 'like-minded' governments in Europe and North America has convinced Vietnam that they can get away with going after civil society groups without facing adverse consequences," Robertson said.

Experts in human rights and international development say Vietnam's treatment of civil society threatens to undermine the JETP because there's no one to ensure the government acts in the public's interest.

Robertson said in a statement Friday that without activists like Hoang, "climate change responses in Vietnam will fall short and fail."