The United States sanctioned two North Korean officials for their role in their country’s missile program, said the US Treasury Department website on Tuesday. The men, Kim Jong Sik and Ri Pyong Chol, are known as two of the three people behind Kims banned rocket program. The Treasury Department said Kim was reportedly a key figure in North Koreas efforts to switch its missile program from liquid to solid fuel, while Ri was reported to be a key official involved in the countrys intercontinental ballistic missile (ICBM) development. "Treasury is targeting leaders of North Korea’s ballistic missile programs, as part of our maximum pressure campaign to isolate (North Korea) and achieve a fully denuclearized Korean Peninsula,” Treasury Secretary Steven Mnuchin said in a statement. “These actions follow Friday’s United Nations Security Council Resolution, which imposed strong new sanctions on North Korea further shutting down its ability to raise illicit funds.” The UN Security Council imposed new sanctions on North Korea last week over a recent ICBM test. The sanctions sought to limit the countrys access to refined petroleum products and crude oil and its earnings from workers abroad. North Korea, which has been working to develop nuclear-tipped missiles capable of hitting the United States, declared those steps to be an act of war and tantamount to a complete economic blockade against the country. Earlier on Tuesday, Russian Foreign Minister Sergei Lavrov informed US Secretary of State Rex Tillerson that Washington’s “aggressive” rhetoric on North Korea was “unacceptable.” He said that this rhetoric only increases tensions in the Korean peninsula. The two officials held a telephone conversation during which they agreed on the importance of holding urgent negotiations on North Korea. They also tackled the latest peace efforts in Syria and the situation in Ukraine.