North Korea has successfully tested the engine of a new intercontinental ballistic missile that would be powerful enough to strike the United States, according to a Korean officials.

The communist country has tested four ballistic missiles since the beginning of the year, despite a the United Nations' Security Council resolution to halt all nuclear-related tests.

North Korea, controlled by leader Kim Jong Un, has previously threatened nuclear attacks against Seoul, South Korea, Washington, D.C., and Manhattan.

The UN Security Council has imposed sanctions on the defiant country, in part to keep it from importing any materials that could be used for nuclear projects.

Experts suspect Kim may be acting more aggressively due to upcoming events in the Korean government that would solidify his leadership role.