"To release the outcome of the investigation is easy," says Kim Tae-woo, senior North Korea analyst at the Korea Institute. "What to do after that is the most difficult part." Seoul is now likely to seek international action, perhaps by asking for tougher sanctions on North Korea from the United Nations Security Council.

The Obama administration announced Tuesday morning that it has struck a deal with other major powers, including Russia and China, to impose new sanctions on Iran, a sharp repudiation of the deal Tehran offered just a day before to ship its nuclear fuel out of the country.

Two leaders from two big regional powers, Luiz Inácio Lula da Silva of Brazil and Recep Tayyip Erdogan of Turkey, took a risk in traveling to Iran and negotiating over the country's contentious nuclear programme. Many said they would fail.

The new British government strongly backs efforts to enact UN Security Council sanctions on Iran aimed at the Islamic state’s nuclear activities, British Foreign Secretary William Hague said Friday.

Brazilian President Luiz Inácio Lula da Silva visits Tehran this weekend in what a US official has called "perhaps the last big shot at engagement" with the Islamic Republic before the UN Security Council applies fresh sanctions against Iran for its refusal to suspend its nuclear program.

China has proposed changes to a U.S.-drafted resolution that would impose tough new sanctions against Iran to pressure the Islamic Republic to start negotiations on its suspect nuclear program, U.N. diplomats said Wednesday.

The United States looks short of Iran options. Even President Barack Obama acknowledges that new sanctions might fail, but has not laid out another plan.

As the US and its allies push for swift UN sanctions against Iran, Turkey urges diplomacy to settle the ongoing dispute over the Islamic Republic's nuclear program.