WASHINGTON — For more than a year, Syria’s civil war has vexed and divided the Obama administration. Now, barely a month before the election, those tensions are finally spilling into the presidential race.
On Sunday, at their second debate, Donald J. Trump and Hillary Clinton both struggled to explain how they would handle the five-year-old war, which President Obama has refused to get drawn into despite a dire humanitarian crisis.
In Mr. Trump’s case, he disavowed the hawkish stance toward Russia of his running mate, Gov. Mike Pence of Indiana, advocating an entirely different set of strategic objectives. In Mrs. Clinton’s case, she threatened to widen a policy split over Syria with the president she served as secretary of state.
Mr. Trump’s response was the more striking one: He countered Mr. Pence’s pledge, made only five days earlier in his debate with Mrs. Clinton’s running mate, Senator Tim Kaine of Virginia, to use airstrikes against the government of President Bashar al-Assad as a response to Russian provocations.
“He and I haven’t spoken, and I disagree,” Mr. Trump said, not just throwing Mr. Pence under the bus, but rolling it over him once or twice.
Mrs. Clinton did not contradict Mr. Obama’s basic policy. But she reiterated her call for a no-fly zone over northern Syria, a step the president and his senior military advisers have long rejected. Such a move, she argued, would pressure the Russians, with whom Mr. Obama’s secretary of state, John Kerry, tried in vain over seven months to negotiate a cease-fire.
Though Mrs. Clinton did not flesh out her proposal, her wording suggested she might be willing to impose such a zone without Russia’s cooperation. That would be a major break with the administration, analysts said — one that could lead to the United States striking government targets and raise the risk of a clash between Russian and American warplanes.
“That’s a really bold statement,” said Andrew J. Tabler, an expert on Syria at the Washington Institute for Near East Policy.
It was the first time that Mrs. Clinton and Mr. Trump had faced off over Syria at any length in their campaign — a remarkable fact, given that it is arguably the most urgent geopolitical crisis in the world. Their exchange captured the mind-numbing complexity of the conflict, the shrinking number of viable options for dealing with it, and the fast-moving nature of events.
“Between now and the election, a quarter of a million people are going to be starving, and going to be forced to surrender to Assad and the Russians,” Mr. Tabler said. “The next president will have to deal with it in pretty short order.”
By the time Mrs. Clinton or Mr. Trump is inaugurated, in fact, the besieged city of Aleppo may well have fallen to Mr. Assad and his Russian backers, its exhausted residents may be dead or displaced, and the rebels who holed up there scattered into the hinterland, where analysts believe they would be likely to wage a guerrilla war against the Assad government.
With few good options for protecting the city that do not involve deploying American troops, it made sense for the candidates not to stake out a hard-and-fast position, analysts said. Mrs. Clinton said she would not commit ground troops to such an effort; Mr. Trump, for his part, argued that Aleppo “basically has fallen” already, which is not accurate.
“No one has an easy answer on Aleppo,” said Philip H. Gordon, a former coordinator of Middle East policy in the Obama administration. “But assuming that the mere threat of force or a handful of airstrikes would quickly make it better would be the triumph of hope over experience. If you decide to go that route you had better be prepared to back it up.”
For Mrs. Clinton, there is the added risk of putting daylight between her and Mr. Obama during a campaign in which the president’s support has proved more important than many expected, given his rising approval ratings and popularity with elusive younger voters. As secretary of state, Mrs. Clinton split with Mr. Obama over providing weapons to the rebels in Syria — a decision the president made after she left the administration.
Mr. Gordon, who now advises the Clinton campaign, said there were other good reasons for Mrs. Clinton not to lay out the details of her strategy.
“Deciding the details of a no-fly zone is not something you do during a campaign,” he said. “You sit in the Situation Room, consult the military, run red teams, and make an assessment.”
Mr. Trump, he noted, does not have experience in the Situation Room to make these judgments. His description of his Syria policy betrayed little preparation and was replete with faulty statements, like the one about Aleppo. To the extent that there was a consistent thread, it was the argument advanced by Mr. Assad and President Vladimir V. Putin of Russia: that the war is a binary conflict between the Syrian government and Islamic terrorists.
For Mr. Trump, the one and only military objective of American forces in the Syria conflict is to focus on the Islamic State — a position that puts him pretty close to Mr. Obama, who has directed the Pentagon to keep its attention on the group, because it, and not Mr. Assad, pose a direct threat to American interests.
“Right now, Syria is fighting ISIS; we have people that want to fight both at the same time,” Mr. Trump said, using an acronym for the group. “We have to worry about ISIS before we can get too much more involved.”
Without question, Mr. Trump has been consistent: In two interviews with The New York Times, in March and July, he argued that it made little sense to try to unseat Mr. Assad if he is fighting the same enemy the United States is battling. Mr. Pence, who has served a decade on the House Foreign Affairs Committee and received a stream of classified briefings on the many-sided conflict, has taken a more traditional Republican view: Don’t let the Russians dominate a proxy war in a small Mideast nation.
During his debate with Mr. Kaine, Mr. Pence argued that the tragedy in Aleppo was so great that the United States is bound, for humanitarian and strategic reasons, to push back against Mr. Putin. On Monday, he said one of the moderators, Martha Raddatz of ABC News, had mischaracterized his position, though she read aloud his own words.
The difference is more than one of nuance. It goes to the heart of two major issues: whether the United States should intervene in humanitarian crises and how it should deal with Russia.
On the first, Mr. Trump seems clear. While he told The Times that he would consider using American force to prevent a humanitarian tragedy, he came up with no examples of where he might do that. On the second, Mr. Trump has sought at every turn to play down Russia’s influence. He has talked about beginning a new relationship with Mr. Putin and avoided any discussion of pushing back against Mr. Putin’s actions in Syria, or his recent efforts to intimidate former Soviet states that are now part of NATO — Estonia, Latvia and Lithuania.
On Sunday, Mr. Trump argued again that there was no evidence Russia was behind the hacking of the Democratic National Committee or of the emails of prominent Americans — including some Republicans. It was an interesting moment to make the case, 48 hours after the director of national intelligence and the Department of Homeland Security publicly blamed Russia, and its leadership, for the actions.
“I don’t know Putin,” Mr. Trump said, trying to put some distance from him. “But I notice, anytime anything wrong happens, they like to say the Russians are — she doesn’t know if it’s the Russians doing the hacking. Maybe there is no hacking. But they always blame Russia. And the reason they blame Russia because they think they’re trying to tarnish me with Russia.”