Obama warns North Korea of tougher sanctions US President Barack Obama has warned North Korea that it will face tougher sanctions if it goes ahead with a planned rocket launch next month. Pyongyang agreed a food aid deal with Washington after committing to halt nuclear and missile tests, as well as uranium enrichment. Obama's comments came on arriving in Seoul after he visited US troops stationed close to the border between North and South Korea, an area he referred to as "freedom's frontier." North Korea will achieve nothing by threats or by provocations. North Korea knows its obligations and it must take irreversible steps to meet those obligations," Obama said. The US and its allies believe that the North's rocket-powered satellite project is merely a cover for a long-range missile test. Pyongyang's atomic ambitions will feature high on the agenda of a global summit on nuclear security, which begins on Monday. The talks kick off just as North Korea ends a one hundred day mourning period for its late leader Kim-Jong-il. One of his sons, Kim Jong-Un, took power after Kim's death. He has been making a series of high-profile visits to military units across North Korea in recent weeks as tensions with the West continue to run high.