Japan has faced difficulty coordinating with the United States to invite President Barack Obama as a state guest in late April, as South Korea has also made a call on Washington for him to visit, sources close to the matter said Monday.

Tokyo has already proposed Obama visit from April 20 to 23 for talks with Prime Minister Shinzo Abe. Foreign Minister Fumio Kishida will visit the United States from Friday to discuss the matter with Secretary of State John Kerry, said the sources.

But the United States has been forced to pay attention to calls from both Japan and South Korea at a time when the two U.S. allies have increasingly confronted each other over a territorial dispute and perceptions of wartime history.