AT&T sure isn’t wasting any time on shoring up their LTE lineup: just a few weeks after the HTC Vivid and Samsung GSII Skyrocket hit the scene, AT&T has announced that the LG Nitro HD will hit the streets on December 4 for $249.99.Better known as the Optimus LTE outside of the United States, the Nitro HD sports a pretty impressive spec sheet. As the name would imply, the Nitro sports a high-definition 4.5-inch AH-IPS running at 720p, and an 8-megapixel camera sits on the Nitro’s rear-end. Under the hood is a dual-core 1.5GHz processor, along with 4GB of internal storage and a pre-installed 16GB microSD card.