For the Constitution to become law, how many states needed to ratify it?

9 States

Explanation:

Instead, on September 28, Congress directed the state legislatures to call ratification conventions in each state. Article VII stipulated that nine states had to ratify the Constitution for it to go into effect.

I believe the answer is: It viewed European interference in the Americas as a threat to US national interests.

It helped colonies in North and South America adopt a democratic form of government.

The monroe doctrine view European interference in America as a form of manifestation of an unfriendly disposition toward the United States.

He believed that all the 'help' that the European give is a camouflage for their true intention, which is wakening United States' government from the position of Ally and slowly taking over control and replace our democracy.