Contemplate vs consider

After reading an article recently, I wondered when one should use contemplate over consider.

I searched for the issue on Google and found that:

In that context, they're essentially the same.

Contemplating is more reflective, thinking about problems that aren't solved, puzzling >over mysteries.

Considering is more like analyzing known choices.

You'd contemplate the mysteries of the universe, you'd consider what kind of car to buy.

(wordreference.com)

Yet, the article I mentioned above, contains the following sentence:

As Iraq erupts in civil war and America again contemplates intervention, that unfinished business should give new urgency to the question of how the United States military controlled the media coverage of its long involvement there and in Afghanistan.

I would say that the possible intervention that is contemplated here is a known choice more than a mystery.

When should I use contemplate over consider?

Consider gives a stronger indication about the willingness to actually do it.

There are several ways in which you can use these verbs:

He contemplated his life. => He thought about his life
He considered his life. => He thought about all the aspects of his life.
He considered his life a success. => He thought his life was a success.

The first two mean as good as the same, and consider and contemplate are almost interchangeable. In the third sentence, contemplate cannot be used.

He contemplates buying a new car.
He considers buying a new car.

The first sentence indicates that buying a new car is something that he might possibly do at some point. He thinks about all the aspects of buying a car in a general way, but he is not necessarily ready to actually make a decision about it.

The second sentence means he actually is trying to reach a decision as to whether or not buy a car. He is looking at the option of buying a car from a positive angle - it may be likely that he will do so.

That is not to say he will buy a car, by the way. If he later tells you:

I considered buying a new car, but then I realised it wasn't worth the money.

That means he evaluated the option, favourably, but in the end he decided that the option was not good.

Now, in the article, if they would write:

The United States consider intervention.

It would strongly indicate that they are looking at it with the idea of actually doing it. This would be quite a string message. However, they are not actually considering it (yet), they are merely thinking about whether it even is an option or not.

'Consider' contains an inbuilt implication that you are weighing the options intently. Using 'contemplate' avoids any suggestion that you are serious about doing the thing in question.