US President Donald Trump announced on Thursday that his landmark summit with North Korean leader Kim Jong Un will take place in Singapore on June 12. It will mark the first ever meeting between a sitting US president and North Korean leader. The announcement was made a day after Pyongyang released three American prisoners. They were greeted personally by Trump upon their return to the US on Thursday morning. US officials said their freedom removed the last major obstacle, providing Trump with tangible evidence that his twin-track policy of engagement and "maximum pressure" was working. "We will both try to make it a very special moment for World Peace!" Trump tweeted. Technically the United States and North Korea are still at war -- a stop-gap armistice ended the brutal three-year war between the two countries in 1953 and around 30,000 US troops remain in neighboring South Korea. Neutral Singapore has long acted as a bridge between the United States and China, with successive prime ministers offering Oval Office occupants cherished geopolitical counsel. When Trump and Kim sit down in the sweltering Southeast Asian city state, the two relatively new and untested leaders face a nuclear puzzle that has eluded seasoned diplomats for decades. A series of US administrations have sent envoys, both official and unofficial, to Pyongyang in the hope of stopping North Koreas provocative nuclear weapons program. Former presidents Bill Clinton and Jimmy Carter visited after leaving office, non-proliferation talks have repeatedly taken place and a deal was even signed in 1994. But despite the optimism of that moment, all efforts to limit North Koreas nuclear program have, to date, failed. And more than two decades and multiple provocative weapons tests after the last accord, the threat from North Korea has only grown. The country is now believed to be on the cusp of developing an intercontinental ballistic missile that could deliver a nuclear warhead to the continental United States. Trump has vowed that he will not let that happen and has demanded that North Korea give up its nukes. So far, the North Korean regime has made vague pledges to "denuclearize" but not said spelled out what that means, when it would happen or how it would be implemented. Later on Thursday, Singapores foreign ministry confirmed it would host the Trump-Kim summit next month. "We hope this meeting will advance prospects for peace in the Korean Peninsula," Singapores Ministry of Foreign Affairs said in a statement. It did not reveal further details of the preparations for the meeting. Various venues had been touted for the Trump meeting, including Mongolia and the demilitarized zone between the two Koreas. Singapore, an affluent Southeast Asian financial hub, was likely chosen due to its neutrality, security advantages and track record of hosting international summits, observers say.