Article snippet: President Donald Trump and White House confirmed on Thursday. He will be replaced by former United Nations ambassador John Bolton — the third person to take on the role during the current administration. “After thirty-four years of service to our nation, I am requesting retirement from the U.S. Army effective this summer after which I will leave public service. Throughout my career it has been my greatest privilege to serve alongside extraordinary servicemembers and dedicated civilians," McMaster said in a statement adding. "I am thankful to President Donald J. Trump for the opportunity to serve him and our nation as national security advisor.” Trump lauded McMaster's service saying "I thank General McMaster and his family for their service and wish them the very best.” McMaster's departure in early 2018 had been planned and expected, especially as Trump re-tools his team ahead of historic talks with North Korea, sources with direct knowledge told ABC News. He was seen as adding a steady and intellectual voice to Trump’s security team, but the president chafed at his style and disposition in Oval Office briefings, the sources said. He also clashed with former Trump advisor Steve Bannon and other top military brass, including Defense Secretary Jim Mattis. He was also reportedly unable to keep the president's attention in complex briefings, correcting him when he doesn't want to be corrected, and seen as a lecturer, the sources said. Three months ... Link to the full article to read more