A South Korean delegation headed back home on Tuesday after concluding working-level trade talks with U.S. officials in Washington this week.

According to sources, the delegation arrived in Washington, D.C., late Sunday and held talks with officials from the Commerce Department and the Office of the U.S. Trade Representative on Monday. 

It marked the first bilateral working-level talks since Presidents Lee Jae Myung and Donald Trump held a summit in Washington on August 25.

The two sides were said to have focused on working out details of South Korea’s pledge to invest 350 billion dollars in the U.S. as part of a trade deal announced on July 30.

The discussions also reportedly centered on coordinating how the investments will be carried out, including who selects the investment targets and how profits are distributed, though the two countries are said to still have differences.