The ambassador of North Korea to the United Nations has warned the United States that its "outrageous" seizure of a cargo ship could have consequences on the future of US-North Korean relations, as he reiterated a demand for the immediate return of the vessel.The Wise Honest, North Korea's second largest cargo ship, was first detained in April 2018 by Indonesia while transporting a large amount of coal. The US announced on May 9 that it had confiscated the vessel because it was carrying coal in violation of UN sanctions, a first-of-its kind enforcement action that came amid a delicate moment in relations with North Korea.In a rare press conference on Tuesday, Ambassador Kim Song said that Pyongyang was closely monitoring Washington's "every move" following the seizure, which he said was aimed at bringing maximum pressure on his country to make it "kneel down"."The United States should deliberate and think over the consequences its outrageous acts might have on the future development," Kim said. The ambassador urged the US to immediately return the ship, describing the seizure as an "outright denial of the underlying spirit" of a joint statement by President Donald Trump and North Korean leader Kim Jong Un after their first summit in Singapore last year "which committed to establishing new bilateral relations".At the summit, Trump promised "security guarantees" to Pyongyang and Kim recommitted to the "complete denuclearisation of the Korean Peninsula".A second summit between the two leaders in late February 2019 in Vietnam collapsed over mismatched demands in sanctions relief and disarmament. The US has called on its allies to maintain economic pressure on North Korea until it takes material steps toward relinquishing its nuclear weapons.The North Korean leader has since aired his displeasure with short-range missile testsapparently aimed at pressuring Washington and Seoul, and declared that the Trump administration has until the end of the year to come up with mutually acceptable terms for a deal to salvage the negotiations. Kim, the ambassador, told reporters that the ship seizure is the "product of an extreme hostile policy of the United States against the DPRK," the initials of the country's official name, the Democratic People's Republic of Korea. He accused the US of violating international law and the 2004 UN Convention on Jurisdictional Immunities of States and Their Property.Kim reiterated that he has asked UN Secretary-General Antonio Guterres to take "urgent measures" to contribute to stability on the Korean Peninsula, but refused to answer a question on what measures.The ambassador listened to about a dozen other questions, including the effect of the seizure of the ship on prospects for a third Kim-Trump summit and on relations between North Korea and South Korea, whether the ship was carrying contraband, the effect of US and UN sanctions, and whether the North would apologise for the death of US student Otto WarmbierKim said he would not answer questions not related to the seizure of the Wise Honest but then only repeated some points from his statement.He ended the news conference saying: "We'll sharply watch the reaction of the United States."