"Some people have said it was offside, others say it was not conclusive. But you must trust the fact that Thierry is very intelligent and when he's left on the wing, he's rarely offside.
"I've seen him given offside more times when he's onside than the reverse. Of course, I'm the Arsenal manager but it's difficult to keep up with him."
Strachan meanwhile, told of the 'history' between himself and the linesman who failed to flag Henry offside, saying:
"You've got to understand that there's plenty of history between myself and Mr Tingey. Five years ago, I got sent off and he accused me of starting a fight as he had seen it clearly.
"But I took a lawyer to the Football Association hearing and there was camera footage that showed I didn't start the fight and it was impossible for him to see me. They got me instead for getting out of my technical area.
"Mr Tingey was kind of embarrassed five years ago and we've had more history since then. My players suffered because of that history, I think. Henry was three or four yards offside."