West Ham United have signed FC Dallas defender George John on loan, with the option to make it a permanent transfer when it expires on 5 March.
The 24-year-old, who has made 95 appearances for the MLS side, has trained with the United States and Greece and is eligible for both.
He told the Hammers website: "Maybe it will take two or three weeks to give me some time to develop and get back into the swing of things.
"Hopefully it will be a bit faster."
He looked set to join Blackburn last summer but the deal never went through.
West Ham manager Sam Allardyce said: "Finding a good central defender at 24 is not an easy task and we have worked very hard to get to this stage. Hopefully it will be successful for both of us."
Dallas head coach Schellas Hyndman told his club's website: "This is an opportunity for George to raise his play to another level.
"He has the opportunity to spend time with a club rich in tradition, playing in one of the top leagues as they work to earn a promotion back to the Premiership. I have no doubt we will see an even better centre-back at the end of this period."