Obama ‘red line’ erased as Bashar Assad’s chemical weapons use goes unchecked by U.S. military

President Obama’s infamous “red line” in Syria seems to have been fully erased.

Amid recent reports Syrian President Bashar Assad again used chemical weapons in his nation’s ongoing civil war, Mr. Obama is taking a much different approach than he did in 2012 and 2013, when the U.S. declared itself on the verge of military intervention after Mr. Assad unleashed sarin gas and other chemical agents despite clear warnings from the White House.

The most explicit of those warnings came in the form of the president’s “red line” declaration, in which he said the use of chemical weapons was a step too far and would bring dire consequences for Mr. Assad and his forces.

The incident was a pivotal foreign policy moment for Mr. Obama and served as a key test of whether he would back up his words with military action.

In the end, the U.S., with the help of Russia, secured an international agreement requiring Syria to give up much of its chemical weapons stockpile. The U.S. never mounted military strikes, and the administration claimed it had used diplomacy rather than force to achieve its objective.

But now it seems clear history is repeating itself, and Mr. Assad again is relying on chemical weapons.

This time, Mr. Obama’s red line is nowhere to be found.

At a press conference last week, the president mentioned no possibility of military strikes and instead said the U.S. expects allies of Mr. Assad, chiefly Russia, to intervene and convince the Syrian government to stop using chemical weapons.

“My commitment was to make sure that Syria was not using chemical weapons and mobilizing the international community to assure that that would not happen. And, in fact, we positioned ourselves to be willing to take military action. The reason we did not was because Assad gave up his chemical weapons. That’s not speculation on our part. That, in fact, has been confirmed by the organization internationally that is charged with eliminating chemical weapons,” Mr. Obama said last Thursday after a Camp David meeting with officials from the Arab monarchies in the Persian Gulf.

“If we have the kinds of confirmation that we need, we will, once again, work with the international community and the organization charged with monitoring compliance by the Syrian government, and we will reach out to patrons of Assad, like Russia, to put a stop to it,” Mr. Obama declared.

There are numerous reports of Mr. Assad using chlorine bombs against rebel forces over the past several weeks. Chlorine is not a prohibited substance under international treaties — it has countless civilian uses familiar to all Americans, from laundry bleach to swimming pool and drinking water cleansers. But its use in bombs, shells or any other weapons is prohibited.

There also are reports the Assad regime has used sarin gas and other chemicals, the mere possession of which is fully banned under international protocols.

Specialists say the change in Mr. Obama’s position stems from a situation on the ground in Syria that is much more complicated than it was in 2012 and 2013. The president first issued the “red line” warning in 2012, and the U.S. was on the verge of bombing Mr. Assad’s forces the following summer.

Two years later, the U.S. still is supporting Syrian rebel forces in their fight to overthrow Mr. Assad but also is targeting one part of that rebel coalition — the Islamist terror group known as the Islamic State, also known by the acronyms ISIS and ISIL.

Meanwhile, the Islamic State is itself fighting against both the Assad regime, a decadeslong U.S. enemy, and the pro-American regime set up in Iraq after the U.S.-led invasion. To that end, it controls large parts of both Iraq and Syria and has set up a self-styled caliphate state in that territory, run according to its understanding of Islamic law.

Foreign policy analysts say this creates a complex geopolitical dynamic in Syria.

“I imagine the fact that we’re now in a situation where we’re sort of implicitly on the same side as the Assad regime might factor in here,” said Benjamin Friedman, a research fellow in defense and homeland security studies at the libertarian Cato Institute. “The administration remains, to me, on a couple sides of the Syrian civil war. We’re not bombing Assad, but we are helping the rebels. We’re going after him even as we’re going after ISIS. So, arguably, we’re on one-and-a-half sides of the Syrian civil war.”

Indeed, while trying to stop Mr. Assad’s use of chemical weapons and also propping up moderate Syrian rebel forces, the U.S. also is mounting operations against the Islamic State, which necessarily helps Mr. Assad somewhat in maintaining control over his country.

On Friday night, U.S. Special Forces killed Abu Sayyaf, an Islamic State leader in charge of the group’s oil, gas and financial operations, during a raid in eastern Syria. U.S. forces also captured his wife, Umm Sayyaf, during the operation, the Pentagon said.

But even as the fight against the Islamic State continues, some specialists say it’s past time for the U.S. to address fully Mr. Assad’s chemical weapons use, despite the geopolitical and logistical difficulty of doing so.

“The reality is that it is not enough to send another fact-finding mission to prove that chlorine has been used. The children who suffocated to death while asleep in their basement are painful-enough proof of what has been going on,” Dr. Zaher Sahloul, president of the Syrian American Medical Society, said in an op-ed on CNN.com late last week.

The organization represents more than 5,000 Syrian-American physicians in the U.S.

“Having seen its so-called red line crossed frequently, the U.S. government should lead the [United Nations] Security Council to implement its own resolutions on Syrian chemical weapons, assign responsibility for the recent attacks and hold the culprits accountable in court,” Dr. Sahloul added.

• Jacqueline Klimas contributed to this report.