President Donald Trump was consistently unprepared for important discussions with other world leaders and often abused key allies to the point that some senior officials, including his former secretaries of state and defense, two national security advisers and his longest-serving chief of staff, determined him to be a danger to national security.

According to a CNN report by Carl Bernstein, which cited White House and intelligence officials familiar with the phone conversations, national security advisers H.R. McMaster and John Bolton, Defense Secretary James Mattis, Secretary of State Rex Tillerson and White House chief of staff John Kelly, said Trump to be often “delusional” in handling foreign affairs.

“The insidious effect of the conversations comes from Trump’s tone, his raging outbursts at allies while fawning over authoritarian strongmen, his ignorance of history and lack of preparation as much as it does from the troubling substance, according to the sources,” Bernstein wrote. “While in office, Director of National Intelligence Dan Coats expressed worry to subordinates that Trump’s telephone discussions were undermining the coherent conduct of foreign relations and American objectives around the globe, one of CNN’s sources said.”

Trump often bullied several leaders of ally countries, but particularly lashed out at United Kingdom Prime Minister Theresa May and Chancellor of Germany Angela Merkel on the phone.

Trump often told May she was weak and “a fool” for her handling of Brexit, NATO and immigration policy.

One of CNN’s sources said Trump also called Merkel “stupid” and “accused her of being in the pocket of the Russians.”

During phone conversations with Russian leader Vladimir Putin and Turkish President Recep Tayyip Erdogan, Trump would frequently brag about himself, his wealth and his accomplishments as president.

He also disparaged his Oval Office predecessors, calling himself smarter and “stronger” than the “imbeciles” and “weaklings” who came before him.

CNN additionally reported that Trump asked that all calls from Erdogan go directly to him, meaning they often bypassed typical National Security Council protocols.

The outlet added that several U.S. policy decisions concerning Syria were directly linked to Erdogan’s calls, including the president’s decision to pull out U.S. troops, thus allowing Turkey to attack Kurds who had helped fight ISIS with the U.S.

White House deputy press secretary Sarah Matthews responded: “President Trump is a world class negotiator who has consistently furthered America’s interests on the world stage. From negotiating the phase one China deal and the USMCA to NATO allies contributing more and defeating ISIS, President Trump has shown his ability to advance America’s strategic interests.”