“It’s largely not a highly disciplined organization,” he said in an interview last month while on a flight back from the Middle East, where he tried unsuccessfully to resolve a bitter feud between Qatar and four Arab nations. “Decision-making is fragmented, and sometimes people don’t want to take decisions. Coordination is difficult through the interagency — has been for every administration.”

Almost from the time of his arrival, Mr. Tillerson has said the department needed to be reorganized, and he has embarked on a wholesale rethinking of its structure. He has hired two consulting companies, undertaken a departmentwide survey and set up five committees to analyze different aspects of the department.

Mr. Tillerson has said the reorganization will be driven by suggestions from staff members, but before the survey process even began he proposed a 31 percent cut to the department’s budget and an 8 percent staff cut — suggesting to many that his mind was already made up. He must give Congress a hint of his plans by Sept. 15 but does not expect to have them fully formed until the end of the year.

Mr. Tillerson’s diplomatic accomplishments have been mixed at best. His biggest achievement came Saturday when the United Nations Security Council voted unanimously to impose sanctions on North Korea for its recent tests of intercontinental ballistic missiles, which required bringing along the Russians and the Chinese. But his effort to resolve the struggle between Saudi Arabia, along with other Sunni powers, and Qatar has made little progress; his department is considered dysfunctional by the Europeans; and policy is entrusted to a tiny group.

Moreover, his reorganization effort has contributed to the paralysis. He has not wanted to appoint under secretaries and assistant secretaries until he understands the new structure. But the career officials sitting in those posts have little authority, and they fear making a career-ending move. His hiring freeze has meant few young people — those with a better sense of how to reach the younger populations around the world — are entering the department. Senior diplomats have left in droves, depleting the building of historical memory.

Wendy R. Sherman, the under secretary of state for political affairs in the Obama administration, noted that the department’s deep bench of talent meant the United States had “more ideas and more capabilities” than any other diplomatic player in the world.

“It is more than concerning that we would stultify that capacity through deep budget cuts, centralization of decision making at State and leaving empty leadership positions,” she said.