South Korean prosecutors indicted a Korean American and four others today for allegedly spying for North Korea in what officials dubbed the biggest spy case since the beginning of reconciliation between the two Koreas.

North Korea’s No. 2 leader said today any progress at revived talks on the communist nation’s nuclear program will depend on the United States, according to a news report, an indication that any breakthrough at the negotiations could be difficult.

A former colleague of embattled South Korean scientist Hwang Woo-suk said today he has asked his university to widen its investigation into the stem cell researcher’s work, and to review earlier purported breakthroughs.