June 21 (UPI) -- A vocal North Korean defector launched 10 balloons from South Korea containing information on the death of U.S. college student Otto Warmbier.
Park Sang-hak, an activist who heads Fighters For a Free North Korea, and six others, launched balloons carrying 300,000 leaflets and 2,000 one-dollar bills, at 5:30 a.m. Thursday, local time, according to Yonhap.
Large hanging pictures of Warmbier and Kim were affixed to one of the balloons. One message attached to another balloon read, "Kim Jong Un, murderer of Otto Warmbier. We mourn the sacrifice of Warmbier. Overthrow the hereditary dictatorship."
Park said Thursday his group strongly condemns the "brutal torture and murder of an innocent 23-year-old American man."
He also said he and others were sending the giant helium balloons to "inform North Koreans" of Warmbier's death.
The United States is expected to take some measures in response to the death of the former detainee, who passed away Monday while under intensive care at a hospital in Cincinnati, Ohio.
Some U.S. lawmakers are calling for a travel ban, while other experts are urging the Trump administration to push North Korea for a clearer answer on what led to Warmbier's coma.
North Korea has stated Warmbier slipped into a coma after contracting botulism then taking a sleeping pill while in custody.
"The United States should never move on. A full accounting needs to include Mr. Warmbier's whereabouts during his last 17 months, precisely when and how he fell ill, and what treatment he received. Americans should be allowed to interview the medical personnel who were involved," wrote former United States assistant secretary of state for East Asia Pacific Christopher Hill.
Hill also said China is key to helping on North Korea, and the two countries need to "better prepare for hypothetical crises."
On Wednesday the United States and China held a high-level meeting in Washington D.C., where conversation focused heavily on North Korea, The Nikkei reported.
"We reiterated to China that they have a diplomatic responsibility to exert much greater economic and diplomatic pressure on the regime if they want to prevent further escalation in the region," said Secretary of State Rex Tillerson.