U.S. President Obama delivered a stern message on Thursday to North Korea and Iran that they risk further sanctions and isolation if they do not rein in their nuclear ambitions.

Obama was joined by his South Korean counterpart Lee Myung-bak who said the two countries were offering a “grand bargain” of political and economic incentives in exchange for Pyongyang’s irreversible de-nuclearisation.

The two leaders held a joint press conference in which Obama announced that the small delegation of American envoys that will travel to Pyongyang for Six Party Talks would do so on Dec. 8

China, Japan, Russia, South Korea and the United States are part of negotiations, called Six Party talks, with North Korea about disarmament.

The United States has no official ties with Pyongyang, and the decision to hold direct talks with the communist nation comes after recent efforts to engage with Iran, which is also internationally condemned for its nuclear activities, proved fruitful.

North Korea conducted its second nuclear test earlier this year as well as test-firing a series of missiles. Neighbours also regarded a rocket launch as a test of its long-range missile technology, although Pyongyang said it was merely launching a satellite.

Earlier this month it said it had produced more weapons-grade plutonium. Its navy also exchanged fire with the south’s for the first time in seven years, with each side accusing the other of violating a disputed sea border.

Relations on the peninsula deteriorated sharply after Lee took power last year and ended his predecessor’s policy of free-flowing aid to the north, angering Pyongyang. At one time, aid from the south equated to around 5% of the north’s estimated $17bn (£10bn) a year economy.

The United States successfully pushed the United Nations Security Council in June to impose tougher sanctions on North Korea in response to the nation’s May 25 nuclear test.

Resolution 1874, which passed with a unanimous vote from the 15-member Council, demands that Pyongyang stop all nuclear and missile activity and demands return unconditionally to the Six Party negotiations. It also imposes a complete embargo on the nation’s export of military material except small arms, gives Council members the power to inspect vessels suspected of contraband.

Financial sanctions have also been tightened, and member states can freeze transactions and assets related to North Korea’s proliferation activities.

A day before Obama’s visit, the KCNA (Korean central news agency) carried an article from the Rodong Sinmun, the North Korean communist party’s newspaper, saying, “The army and people… are dealing merciless blows at the imperialists, countering their reckless moves with the toughest measures. The Korean people are growing stronger in their faith and will to protect socialism to the last from the ever-more undisguised moves of the U.S. imperialists and settle accounts with them without fail.”