WASHINGTON, July 20 (UPI) -- The chairman of the U.S. Joint Chiefs of Staff said Sunday an Iraq withdrawal timeline could have dangerous consequences.

Appearing on "Fox News Sunday," Adm. Mike Mullen said the so-called time horizon being contemplated in negotiations between Washington and Baghdad "doesn't speak to" timetables. He said he wasn't sure how quickly Iraq would be able to assume command and U.S. troops could be removed.

"Well, I think -- I'm not yet able to put an exact time line on it, per se," Mullen said. "I think the strategic goals of having time horizons are ones that we all see, because eventually we would like to see the U.S. forces draw down and eventually all come home."

When asked about a timeline for withdrawing all combat troops in two years, Mullen said "the consequences could be very dangerous in that regard."

"I'm convinced at this point in time that coming -- making reductions based on conditions on the ground are very important," he said.

Mullen said the time horizons under discussion do not involve dates or goals for troop withdrawals.

"This right now doesn't speak to either time lines or timetables, based on my understanding of where we are," he said.

Mullen said if conditions he saw in Iraq when he was there last week "continue to improve, we should be in a position to start bringing our troops home."