By Alex Jensen

SEOUL

North Korea's Foreign Ministry stated Thursday that "one cannot expect any progress in the implementation" of Pyongyang's denuclearization agreement with the U.S. if Washington maintains its emphasis on sanctions.

The reclusive state took steps such as dismantling its nuclear test site even before the unprecedented North Korea-U.S. summit on June 12, but the two sides have still failed to decide any timeline for Pyongyang to give up its existing nukes.

Earlier in the day, the North's official Rodong Sinmun newspaper insisted the first step towards peace should be formally ending the 1950-53 Korean War, but Washington has maintained that Pyongyang must denuclearize before securing either a peace treaty or sanctions relief.

North Korea then released a statement following up on Foreign Minister Ri Yong-ho's criticism of the U.S. last weekend for not carrying out simultaneous measures after Pyongyang also allowed the U.S. to pick up war remains last month -- even though Washington did suspend joint military drills with South Korea this summer.

The ministry threatened to hold back on denuclearization "as long as the U.S. denies even the basic decorum for its dialogue partner and clings to the outdated acting script which the previous administrations have all tried and failed," according to a spokesperson quoted by the North's state-run KCNA news agency.

However, the statement offered the U.S. a way forward if it responds sincerely "even at this belated time".