The Afghan president's push to delay a security pact with the U.S. has undermined confidence in Afghanistan's future, testing international support for the country at a crucial moment, the U.S.-led coalition's top commander said. U.S. Marine Corps Gen. Joseph Dunford warned that President Hamid Karzai's failure to quickly sign the agreement could weaken the Afghan economy, embolden the country's powerful neighbors and ultimately lead to the collapse of the country's security forces. "I don't know if he fully realizes the risks," Gen. Dunford said in an interview with The Wall Street Journal. "He certainly understands it from an Afghan perspective. I don't know if he fully appreciates what the implications are for the United States." The lack of clarity about the security agreement, which is needed for a U.S.-led force to remain in Afghanistan after the coalition's current mandate expires in December 2014, is already exacting a toll, Gen. Dunford said. Over the past week, Karzai has stepped up his confrontation with Washington over the bilateral security agreement, which was approved by Afghanistan's Loya Jirga assembly on Sunday, after more than a year of difficult negotiations. In addition to providing a framework for long-term U.S. military presence here, the deal is a prerequisite for billions of dollars in critical military and civilian aid to Afghanistan. Despite a request for prompt ratification by the Loya Jirga, Mr. Karzai in recent days raised several new preconditions before signing the agreement, asking for more time and saying the U.S. must first jump-start the peace process with the Taliban insurgents.