U.S. Secretary of State Marco Rubio will skip a meeting of foreign ministers from the leading rich and developing nations, known as the Group of 20, that starts on Thursday.

Amid diplomatic tensions between host South Africa and the Trump Administration, the U.S. will be represented at a meeting of foreign ministers by the acting ambassador to South Africa.

Secretary of State Marco Rubio has decided to skip the upcoming G20 foreign ministers’ meeting in Johannesburg, South Africa, marking the first major international gathering he’ll miss since taking office last month.