United States and the United Nations the invasion of South Korea by North Korean troops, leading to the UN sanctioned Korean War. Later, the U.S. persuaded all permanent members of the Security Council to authorize force against Iraq after it invaded Kuwait in 1991. This was a major step toward U.S. and Russian reconciliation after the end of the Cold War. Since 1991, the United States has been the world's dominant military, economic, social, and political power (not to mention hosting the UN Headquarters itself in New York City); the United Nations was not designed for such a unipolar world with a single superpower, and conflicts
Headquarters of the United Nations the complex opened in 1950, were expected to take about 7 years to complete. When completed the complex is also expected to be more energy efficient and have improved security. A temporary $140 million "North Lawn Building" was built to house the United Nations' "critical operations" while renovations proceeded. Work began on May 5, 2008, but the project was delayed for a while. By 2009 the cost of the work had risen from $1.2 billion to $1.6 billion with some estimates saying it would take up to $3 billion. Officials hoped the renovated buildings would achieve a LEED Silver rating.