Will Obama reconsider arming Syrian rebels? This week could be key.

President Obama has long been loath to arm Syrian rebels, worried that the weapons could fall into extremists' hands. But with the rebels faltering, he could reconsider.

With the tide in Syria’s civil war showing signs of shifting in favor of President Bashar al-Assad – especially as thousands of Hezbollah fighters have poured into the country in recent months to fight on the government’s side – the Obama administration is taking a fresh look at arming Syria’s rebels.

President Obama could decide as early as this week to alter his Syria policy and shift from providing only nonlethal assistance to providing weapons to carefully vetted moderates among Syria’s disparate rebel groups, administration officials say.

That may sound familiar, since some administration officials have asserted privately since shortly after Mr. Obama’s reelection in November that a decision to arm the rebels was imminent. Closer to the truth is that a heated debate over the advantages and drawbacks of arming the rebels has continued in the White House since the US election.

The debate is likely to continue this week, as some officials are expected to advocate imposition of a no-fly zone over arming the rebels. Susan Rice, the US ambassador to the UN whom Obama has just named to replace Tom Donilon as his national security adviser, is said to favor a no-fly zone – an option other administration officials insist is unlikely to win presidential favor.

What has changed recently – and what could tip the balance now in favor of providing weapons that have been denied for the better part of two years – is how Mr. Assad and his forces appear to have regained the upper hand in the 26-month-old civil war.

Earlier this year, reports from the war-smashed country referred to a “beleaguered” Assad, but now that adjective is applied more regularly to the rebels, who have suffered a string of recent setbacks – including the loss last week of the town of Qusayr near the Lebanese border.

Now reports are circulating that a resurgent Assad may be about to launch an offensive on the strategic city of Homs, the center of which is held by the rebels. Losing Homs could cut the rebels off from the southern part of the country and could be a decisive blow, some regional experts say.

Noninterventionist voices inside the White House and out have long argued that weapons the US provided to the rebels could end up in the hands of the more extremist Islamist forces fighting against Assad – and could someday be turned against the US or US interests.

While that concern has not waned, some US foreign policy analysts say it has been eclipsed by worries that Assad’s ability to hang on to power would constitute a considerable and dangerous victory for Iran. That is all the more true since much of Assad's momentum has come with the aid of as many as 5,000 Iran-backed Hezbollah fighters, not to mention Iran’s continuing material aid.

Opponents of arming the rebels say such an action would doom a recent effort by Secretary of State John Kerry to convince Russia, a key Assad ally, to join the US in sponsoring a Syria peace conference. Skeptics of the peace conference plan note that the conference, originally set for May and now envisioned for July, may never get off the ground

In the meantime, they add, Assad is making crucial gains across the country.

In a letter to Obama this week, Sen. Bob Corker (R) of Tennessee, the top Republican on the Foreign Relations Committee, urged the president to provide lethal assistance to moderate factions among the rebels. This, he said, would deal a blow not just to Assad, but also to the “radical Islamist groups” among the rebels that threaten to gain the upper hand.

“Acting now and offering lethal aid directly to our allies in the opposition will shift momentum away from radical Islamist groups, the Assad regime and its militias toward more moderate elements and could help alter the balance of power on the ground at a time when negotiations over a political settlement have stalled,” Senator Corker wrote.

Secretary Kerry, who had been scheduled to travel to the Middle East this week, canceled his trip in order to take part in the White House discussions on Syria. As a senator before taking his current job, Kerry spoke out in favor of arming the rebels.

More recently, Kerry has put considerable effort into coaxing his Russian counterpart, Sergei Lavrov, into backing the idea of a peace conference, to be jointly sponsored by the United Nations, the US, and Russia, and which would aim for a political solution to the Syrian war.

The two powers have agreed on the idea of holding a conference, but disagreements over the fate of Assad have put off setting details such as a conference date. Rebel groups insist that a deadline be set for Assad’s departure from power, while Assad has said that any conference on Syria should not be held based on any preconditions.

Assad has said he plans to run for another term in office next year.