U.S. President Donald Trump and South Korean President Lee Jae-myung have yet to hold a phone call, breaking with the longstanding custom in which newly inaugurated leaders from both countries typically speak within hours of taking office.

Citing scheduling constraints and time differences, South Korean presidential officials told local media that the two sides are still “coordinating” the call’s timing but did not offer a target date. In the meantime, Lee has received congratulatory messages from Chinese leader Xi Jinping, Japanese Prime Minister Shigeru Ishiba and U.S. Secretary of State Marco Rubio.