Afghans queueing at ballot boxes this weekend can be forgiven some foreboding about their country's future amid the chaos now being unleashed in Iraq almost three years after US troops withdrew.

While the political, ethnic and security situations in the two countries are vastly different, both nations have been at the center of US wars, both are plagued by a homegrown insurgency and both still suffer from weak institutions vital to ensure stability and growth.

After months of hesitation, US President Barack Obama has finally set a timeline for the withdrawal of the last US troops from Afghanistan.

Come January 2017, the Afghan army will be on its own militarily to face resilient Taliban militants, on the rise again after being routed from power by the US-led invasion in 2001.

The hopes are that the Afghan forces will be stronger and more cohesive than their Iraqi counterparts who this week -- despite billions of US dollars in training and equipment -- just melted away in the face of an onslaught by jihadists from the Islamic State of Iraq and the Levant.

But analysts warned the future for Afghanistan could be just as fraught with danger.

Many had believed "Al-Qaeda in Iraq, which is now rebranded as ISIL, had been decimated, defeated and decapitated by the (US troop) surge," said Bruce Riedel, a security expert with the Brookings Institution.

But he warned that "the very fast resurgence of Al-Qaeda in Iraq" after US troops withdrew on December 31, 2011 "bears an ominous parallel" for Afghanistan.

Much of ISIL's rise is attributed to the festering civil war in neighboring Syria, as well as the failure of the Iraqi leadership to heal sectarian divides between Sunni and Shiite Muslims.

"One lesson for Afghanistan is be ready for some kind of exogenous shock, understand that there are things elsewhere, beyond Afghanistan, that could make things turn the wrong direction," said Christopher Chivvis, a senior political scientist with the RAND Corporation.

A positive factor though is that both Afghan presidential hopefuls have said they will sign a deal with Washington to allow US forces to stay.

Iraqi leaders refused any such pact, leading to an abrupt 2011 withdrawal.

Experts argued there is still time to step up the training of Afghan security forces, who have already begun building confidence and know-how by taking the lead on the ground.

"The Afghan National Army has been tested for the last year. It has been conducting more than 90 percent of combat operations and its track record is pretty good," Riedel said.

Chivvis agreed military training must be a priority. But he warned against the "giant sucking sound" as international attention turns away from Afghanistan, which has less strategic value to the US than Iraq.

"As the withdrawal approaches, there's an acceleration of a decline in resources, a decline in interest and also a decline in cooperation both in the US government and between international actors on the ground," Chivvis said.

"They are no longer cooperating for the same common end. They're trying to get out."

US officials have called for even greater political engagement to fill the vacuum including efforts to boost a peace bid between Afghanistan and the Taliban.

"When it comes to Afghanistan, obviously we believe there needs to be a political reconciliation effort between the Afghans," State Department deputy spokeswoman Marie Harf said. "We're going to keep building their capacity."

While Afghans may heave a sigh of relief that US troops are leaving their villages, many, especially women, fear a gradual return to some of the excesses of the harsh Taliban rule.

"The Obama administration may hope that Afghans will interpret the president's decision as a vote of confidence in their institutions. It is far more likely, however, that they will interpret it as a signal of abandonment," said Scott Smith from the United States Institute for Peace.

Riedel also voiced concerns that Obama's "reckless" decision to set an "egg-timer" on the US withdrawal had merely signaled to the insurgents that they just have to sit tight until late 2016.

For neighboring Pakistan -- one of the Taliban government's sole international backers -- Obama's announcement was an "enormous gift," said the former career Central Intelligence Agency officer and presidential advisor.

"They now know when they can give their clients all the help they need to win the war. And they know they just need to wait until January 2017," Riedel added.

Smith, writing in Foreign Policy magazine, stressed that if the next Afghan government is vulnerable and lacks international support, "the predatory currents of Afghan politics will combine with the unhelpful rivalries of Afghanistan's neighbors conditioned to use Afghanistan as a proxy battlefield."