US Secretary of State Hillary Clinton called on Myanmar Thursday to cut "illicit ties" with North Korea and said the regime had given assurances that it was not cooperating with Pyongyang. "I was frank that better relations with the United States will only be possible if the entire government respects the international consensus against the spread of nuclear weapons," Clinton told reporters. "We look to Naypyidaw to honour UN Security Council Resolutions 1718 and 1874 and sever illicit ties with North Korea," she added. President Thein Sein gave "strong assurances" that Myanmar would abide by the UN resolutions, which ban weapons exports from North Korea, Clinton said during a landmark visit to the isolated capital Naypyidaw. Her aides have, however, played down defectors' accounts of nuclear cooperation between the two authoritarian countries, saying the top US concern relates to missile technology. Thein Sein also said that Myanmar was "strongly considering signing the IAEA additional protocol and that they are already engaged in dialogue with the IAEA", according to a senior State Department official speaking on condition of anonymity. The IAEA, or the International Atomic Energy Agency, is the nuclear watchdog of the United Nations. Signing its additional protocol would allow the IAEA to carry out inspections of suspected clandestine nuclear sites. Allegations of nuclear cooperation between Myanmar and North Korea have been a top concern for US lawmakers. Republican Representative Ileana Ros-Lehtinen, a frequent critic of President Barack Obama who heads the House Foreign Affairs Committee, said that the weapons concerns made US outreach to Myanmar problematic. "Secretary Clinton's visit represents a monumental overture to an outlaw regime whose DNA remains fundamentally brutal," she said in a statement in Washington.