The U.S. State Department said on Saturday that the United States is "disappointed" in North Korea's recent actions to sever ties with South Korea, urging the communist nation to "avoid provocation" and return to diplomacy and cooperation.

A spokesperson for the department gave the response to an inquiry by Seoul-based Yonhap News regarding statements issued on Saturday by North Korean leader Kim Jong-un's powerful sister Kim Yo-jong and a senior North Korean official.

Kim Yo-jong threatened in the statement that Pyongyang will take retaliatory measures against South Korea that involve the military, hinting at a possible destruction of an inter-Korean liaison office.

Kwon Jong-gun, director general of the North's United Front Department, said South Korea should stop "nonsensical" talk about denuclearization, claiming Seoul is not qualified to discuss or "poke its nose into" nuclear talks between Washington and Pyongyang.

Regarding the statements, the spokesperson of the State Department said that the United States has always supported progress in inter-Korean relations, and it is disappointed in the North's recent "actions and statements."

The spokesperson then said the Unites States urges North Korea to "avoid provocation" and return to diplomacy and cooperation, adding Washington remains in close coordination with its ally, South Korea, on efforts to engage North Korea.

The department issued a similar response last week when North Korea cut off all communication lines with South Korea, but the latest statement included the expression of "avoid provocation."