The debate about the future of U.S. troops in Iraq has once again devolved into a parsing of words. Beyond the semantic maneuvering, however, it is clear that the context and tone of the discussion of when U.S. troops will leave Iraq has fundamentally changed. The difficulty now, both in Baghdad and Washington, is to ensure the discussion remains grounded in reality, not political expedience.

Democratic presidential contender Barack Obama has often said he would withdraw U.S. troops from Iraq 16 months after he takes office. Republican leaders have decried such timetables and deadlines, saying they will simply embolden insurgents in Iraq.

The debate shifted last week when Iraqi leaders began talking of timetables.

In an interview with the German publication Der Spiegel last week, Iraqi Prime Minister Nouri al-Maliki supported a short timeline for American troop withdrawal. Asked when he thought U.S. troops might begin leaving, Mr. Maliki said: “As soon as possible, as far as we’ re concerned. U.S. presidential candidate Barack Obama talks about 16 months. That, we think, would be the right time frame for a withdrawal, with the possibility of slight changes.”

Is that an endorsement of Mr. Obama? “Those who operate on the premise of short time periods in Iraq today are being more realistic. Artificially prolonging the tenure of U.S. troops in Iraq would cause problems,” the prime minister said. “Of course, this is by no means an election endorsement. Who they choose as their president is the Americans’ business. But it’ s the business of Iraqis to say what they want. And that’ s where the people and the government are in general agreement: The tenure of the coalition troops in Iraq should be limited.”

The next day, the U.S. military distributed a clarification written by the prime minister’ s spokesman Ali Dabbagh, who said the German magazine “misunderstood and misinterpreted” Mr. Maliki’ s comment. It is hard to believe that the magazine misinterpreted Mr. Maliki’ s comments about a quick withdrawal since he mentioned it at least three different times during the interview. Still, Mr. Dabbagh referred back to joint statements by Mr. Maliki and President Bush, which spoke of “a general time horizon for meeting aspirational goals such as & the further reduction of U.S. combat forces from Iraq.”

The situation got more complicated when the spokesman, Mr. Dabbagh said Monday that the 16 months called for by Mr. Obama was an “Iraqi vision.” “We can’ t give any schedules or dates, but the Iraqi government sees the suitable date for withdrawal of the U.S. forces is by the end of 2010,” he said.

The White House was left to stress that a withdrawal would not be arbitrary, but based on conditions on the ground.

The only one not making any reference to timelines or time horizons is Republican presidential candidate John McCain. “When you win wars, troops come home,” he said Monday in Kennebunkport. The problem is Mr. McCain has never defined winning in Iraq so it remains unclear when he believes U.S. troops could come home, although he has mentioned 2013.

Expect more semantic sparring, but also expect larger numbers of U.S. troops to leave Iraq in coming months.