The tweet says it all.
Columbus Crew Midfielder Tony Tchani has chosen and it's not the United States. He's been called up by both countries and most recently by the USMNT in January for Friendlies against Iceland and Canada. January 31st was his debut with the USMNT side. Those friendlies did not cap-tie him to the USA, however. He's been called up to Cameroon and came on as a substitute in an African Cup Of Nations qualifier against South Africa today.
Cameroon tied South Africa 2-2.
One the surface this loss doesn't appear to have much significance to the USMNT.