"if" block without curly braces makes subsequent "else if" nested

AFAIK, if an "if" block is not provided the curly braces then only 1 statement is considered inside it. e.g.

if(..)
  statement_1;
  statement_2;

Irrespective of tabs, only statement_1 is considered inside the if block.

Following code doesn't get along with that:

int main ()
{
  if(false)  // outer - if
    if(false)  // nested - if
      cout << "false false\n";
  else if(true)
    cout << "true\n";
}

Above code doesn't print anything. It should have printed "true".
It appears as of the else if is automatically nested inside the outer if block. g++ -Wall issues warning, but that is not the question here. Once you put the curly braces, everything goes fine as expected.

Why such different behavior ?
[GCC demo: without braces and with braces].