Published: Jul 04, 2010 8:22 PM EDT
Updated: Jul 04, 2010 5:17 PM EDT

KABUL, Afghanistan (AP) - Gen. David Petraeus says the Afghan government and the international coalition forces are engaged in "a contest of wills" with the Taliban and their allies.
      
Petraeus formally assumed command of U.S. and coalition in Afghanistan today, calling it "a critical moment" in the war.
      
Speaking outside NATO headquarters in Kabul, Petraeus told those gathered that insurgents are trying to undermine public confidence in the Afghan government and the international community by killing and maiming civilians.
      
He said it's important to demonstrate to the Afghan people and to the world that "al-Qaida and its network of extremist allies won't be allowed to again establish sanctuaries in Afghanistan" from which they can launch attacks.
      
Petraeus also praised his predecessor, Gen. Stanley McChrystal, saying progress made in recent months is in many respects the result of "the vision, energy and leadership" he provided.