Another year has passed in Syria, with no end in sight for a conflict that has claimed 200,000 lives, injured a million and displaced nearly half the population.

In four years, the Obama administration has sought an effective strategy on Syria, to no avail.

2015 Could Be Watershed for Syria Conflict

But in November elections, Republicans gained control of the Senate, and some analysts suggest that in next year’s session, Congress could push for the U.S. to take a more aggressive stance against Islamist militants and the regime of Bashar al-Assad.

2015 Could Be Watershed for Syria Conflict

Two rounds of peace talks at the start of 2014 ended without agreement, and the spring saw the Syrian regime regain two key rebel strongholds, Yabroud and Homs.

2015 Could Be Watershed for Syria Conflict

Syrian President Bashar Al-Assad announced elections June 3, which he won - predictably - by a landslide. That same month, the United Nations announced that it had of Syria’s chemical weapons—and the extremist Islamic State group (IS) in Iraq and Syria announced it had established a caliphate.

From this point on, the rebels have been fighting a war on two fronts.

On the one front, Assad’s military carried out 2,000 airstrikes between October 20 and November 29 alone, according to the , killing more than 500 Syrians, even as U.S. planes were in Syrian skies.

The regime looks poised, analysts say, to take , unless the United Nations can achieve a proposed freeze in fighting, which would allow much-needed aid to reach the embattled population and give parties a brief opening for diplomacy.

On the second front, as Republican Senator Marco Rubio of Florida recently cautioned in the , is that the Islamic State group now reaches from North Africa through the Middle East, Pakistan and South Asia and into Southeast Asia.

“Mainstream rebel forces are losing battle after battle to ISIS, as well as to the al-Qaida affiliate, Jabhat Al Nusra,” said of the Brookings Institution's Center for Middle East Policy. ISIS is another name for the Islamist group.

, recently told the Security Council that she had “run out of words” to fully explain the “brutality, violence and callous disregard for human life” witnessed in Syria today.

“The parties to the conflict continue to ignore the most basic principles of humanity,” Amos said. “In many parts of Syria the level of violence has worsened, with civilians continuing to pay heavily with loss of life, serious injuries, psychological trauma, ongoing and recurring displacement and massive damage to property and infrastructure.”

In September, U.S. President Barack Obama announced a two-fold strategy for degrading and destroying IS in Syria and Iraq.

In Syria, the U.S. and, to a lesser extent, five Arab allies have conducted targeted airstrikes against IS, mostly at Kobani, near the Turkish border.

But the impact of these strikes may be more psychological than anything else, said Northeastern University’s terrorism expert .

“I think our airpower was effective, maybe not in qualitatively degrading the IS, but more importantly in terms of puncturing their aura of invincibility,” he said.

The of the strategy - training and arming “moderate” rebels - won’t begin until March 2015. But analysts said it may be difficult to find willing partners to work with the U.S. and to properly vet fighters.

“We’re talking here about $500 million to train about 5,000 fighters,” Hamid said. “When we are talking about a military theater in which there are more than 100,000 fighters from a whole variety of rebel grounds, 5,000 fighters are just a drop in the bucket.”

And what, Hamid asks, will those fighters be doing?

“Based on [Joint Chiefs of Staff chairman] General Martin Dempsey’s comments and the comments of other officials, this seems to be a primarily anti-ISIS fighting force,” he said. “But how do you convince 5,000 fighters to hold their fire against their primary enemy, the Assad regime, and focus just on ISIS?”

If the U.S. wants to gain the trust of the Syrian opposition, Hamid said, it would have to admit it got things wrong and address the issue of the Assad regime itself.

“The longer that Assad is in power, the longer Syria is divided,” said Andrew J. Tabler, senior fellow in the Washington Institute’s .

“And the longer Syria is divided, the longer ISIS has free rein over the country.”

Mid-term elections held in November saw Republicans win control of the U.S. Senate and that could change the equation, Abrams said.

“There are some real differences between Congressional Democrats and Republicans with respect to how to prosecute the war against the Islamic State,” Abrams said.

“And there are a lot of inconsistencies within the parties, particularly in the Republican party.”