How will the "bring our girls back" campaign have any effect?

276 kidnapped Nigerian girls have been kidnapped, and are being sold into sex slavery. Many Hollywood stars and other noted individuals are posting pictures of themselves holding signs that say things like Real Men Don’t Buy Girls or “Bring Back Our Girls”.
I have no doubt this is a good cause, and the tragedy of what is happening must be addressed, but exactly how will these selfies with signs do anything?
It’s not like the Nigerian kidnappers will be spending their time on Facebook.
What do you think should be done?
Should a military intervention occur?
Can such an intervention be successful?
Will these signs have any influence on the outcome?
Are these signs putting pressure on the politicians more than the kidnappers?
Isn’t the fact that all these girls have been kidnapped and are being sold into sex slavery enough to promote action?