Donald Trump has fired Secretary of State Rex Tillerson, and hopes to replace him with CIA Director Mike Pompeo. Over Tillerson’s short tenure at the Department of State, he and President Trump did immeasurable damage to United States diplomacy and foreign policy.

The unprecedented staff turnover under President Donald Trump raises serious concerns about the State Department in the long term. As top officials are unceremoniously pushed out of the State Department, new talent is not replacing them. Foreign Service Association President Barbara Stephenson wrote that in 2016 the State Department hired 366 new foreign service officers but that number is expected to drop to 100 this year. There were 431 two-star Minister Counselors just after Labor Day, but only 369 by the end of the year. Nearly 60% of political appointment jobs in the State Department are not filled.

As with the broader department, the U.S. diplomatic corps is being razed under President Trump. He has failed to nominate ambassadors in key countries, including South Korea, Egypt, and Germany.

Trump’s ambassador selection lags other presidents as well. In August 2009, President Obama had appointed 27 career ambassadors and 38 political ambassadors, while at the same period in 2017 Trump had appointed just 36 ambassadors. In Trump’s first year in office, the U.S. lost 60% of its career ambassadors. The hemorrhaging of career talent at the ambassador level leaves the United States with a diplomatic vacuum abroad.

Under Tillerson, the State Department was fractured by slow and nonexistent appointments, and the problem was exacerbated by the turnover of career foreign service officials at all levels. Leadership at the top was missing in action because Tillerson’s voice in decision-making was shelved early, and clashes between Tillerson and Trump only deepened the divide. With fewer established diplomats to run embassies or communicate with foreign officials, the Department of State has become a weaker apparatus for the exercise of national interest. As a major world power, the U.S. failing to represent itself abroad serves to make America anything but “great.”