Montreal Impact manager and Arsenal icon Thierry Henry insists Major League Soccer is heading in the right direction, but patience is needed.

America's top-flight competition is celebrating its 25th anniversary this year, but its standards are still considered well below the major leagues in Europe and South America.

Younger players from Europe and Mexico are increasingly making the switch to the States, and Henry says the league must remain patient during its development.

"The fact that now teams are buying players from the Mexican league and trying, managing, to get players from Europe earlier, I don't think that would have happened before," Henry told reporters on Tuesday. "The league was always trying to get guys at the end of the contract and try to see if they would come or not. Now, teams are going and getting those players from the Mexican league early, straight away, young age. Argentina, I'm not going to name all the countries, but that would never happen before and so that's a sign that the league is evolving.

"It's very difficult because this is the 25th anniversary of the league this year and so you have other leagues that have been playing for 100 years already, some a bit less. You have clubs in Europe that are 125 years old. It's difficult to battle history, so let the league grow and reach.

"I don't know how far they can go, this league can go. It's up to us obviously now I'm back in, to make sure that we can elevate the league as much as we can. This league has no limits for me, but you need time to reach that level, if you know what I mean."