Basic Foul Question

[Welpe]

Hey folks...I don't work soccer but I take in a match now and then. I was watching the second half of the US v. Trinidad/Tobago match and noticed something that I've been wondering about. While the ball was deep in Trinidad's side of the field (sorry...pitch), a Trinidad defender was controlling the ball with his side to a US attacker. Everytime the US player tried to go for the ball, the Trinidad player would extend his arm out fully and give the US attacker a hard shove. He did this 3 or 4 times before he cleared the ball.

I was under the impression this would be a foul by a strict reading of the rules but obviously the CR felt otherwise. Is this amount of contact usually acceptable at the international level? At what level would you consider whistling this as a foul (if it even is a foul)?

Thanks and sorry for the basic question.