North Korea's official KCNA news agency, referring to the imprisoned men, Jeffrey Fowle and Matthew Miller, said "their hostile acts were confirmed by evidence and their own testimonies."
Asked about the report, US State Department spokeswoman Jen Psaki told reporters, "Out of humanitarian concern for Mr. Fowle and Mr. Miller and their families, we request North Korea release them so they may return home."
She also called on North Korea to pardon and release Kenneth Bae, a Christian missionary who was arrested in November 2012, convicted and sentenced by North Korea's supreme court to 15 years hard labor last year.
"We request North Korea pardon Kenneth Bae and grant him special amnesty and immediate release so he may reunite with his family and seek medical care," Psaki said.
The United States has no diplomatic relations with North Korea and works through Swedish diplomats when US citizens are detained.
Psaki said Swedish officials had visited Fowle on June 20 and Miller on May 9 and June 21. It is unclear whether both men are being held in the same location.
Psaki declined to give additional information citing concerns for their safety.