The Iron Curtain

Not to be confused with Iron Curtain, the removed level.

The Iron Curtain is the 6th level of Bloons.

Completion
All you have to do is aim above the Metal Blocks, then pop the bloons behind them and repeat. Do not power the dart too much, while aiming at the north-eastern side, as the dart may go over the bloons.

Trivia

 * Blocks make their first appearance in this level. This time, they are Metal.
 * The name is a reference to the nickname of the historic Berlin Wall, which divided Germany between East and West Germany during the cold war.