Mexico's drug wars are spilling over into the US, forcing Obama's administration to refocus attention on the border.
The buildup in Ciudad Juárez, an entry point for drug smuggling on the US border, is meant to stop vicious fighting between drug cartels.
The US State Department has issued a new travel advisory warning of 'large firefights' across the country.
At least 35 people were killed in 24 hours in the worst spate of bloodshed yet this year.
Freedom of press is under siege in Mexico. Calls grow for a new law to make such attacks on the media a federal crime.