MOSUL, Iraq - The top U.S. military officer says Iraq's indecision on whether to ask American troops to stay beyond the end of the year is pushing the U.S. close to the point where a smooth withdrawal will be jeopardized.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, says the U.S. has to know what the Iraqi government wants. He arrived in Iraq Monday.

His visit comes as the U.S. is growing increasingly frustrated with Iraqi leaders' failure to agree on whether they will ask American troops to remain in the country beyond the end of the year. That's when all but a small contingent of forces are required to leave under an agreement signed in 2008.