Gen. David H. Petraeus, the head of the United States Central Command, said Sunday that the battle being fought in the Taliban stronghold of Marja was the “initial salvo” in a military campaign that could last 12 to 18 months.

In an interview on NBC’s news program “Meet the Press,” the general, who oversees the wars in Afghanistan and Iraq, sought to put the Marja battle “into context” by explaining its part in the overall effort by American, Afghan and other forces to defeat the Taliban. He said that international forces had spent recent months mapping strategy, gathering resources and preparing the leadership of a “comprehensive civil-military campaign.”

Saying that 5,400 of the 30,000 additional troops President Obama has promised to deploy were already on the ground, General Petraeus added that Special Forces were playing a major role. “We have more of our Special Operations forces going in on the ground, and you’ve seen the results,” he said, “with more Afghan shadow governors, the Taliban shadow governors being captured, more of the high-value targets being taken down.”

General Petraeus said that American troops had encountered tough fighting from a force he called both “formidable” and “a bit disjointed at this point.”