President Joe Biden’s national security adviser, Jake Sullivan, cautioned his Russian counterpart last week that “any possible Russian decision to use chemical or biological weapons in Ukraine” would have “consequences.”

This White House lacks any credibility to issue such a threat — as our Middle East allies well know.

The last time a US president attempted to dissuade a despot from deploying chemical weapons in a bloody conflict was 2013, when Sullivan’s former boss, President Barack Obama, warned Syrian President Bashar al-Assad that attacking the Syrian people with chemical weapons amounted to a “red line” that if crossed would result in “enormous consequences.”

Assad didn’t heed Obama’s warning. He ultimately carried out dozens of chemical attacks against his own people. Obama (and his vice president, Joe Biden) hoped to gain overwhelming international support to intervene. But Europe was divided, so Obama looked to Congress, then decided against pushing for congressional authorization. In the end, the president stood down, destroying whatever credibility America had in the Middle East.

One can only imagine how this display of indecision appeared to Russian strongman Vladimir Putin, who sought to lessen American influence in the region.

Once it became clear Obama would not intervene, Putin made his move. He sent aircraft to Syria, targeting the Sunni rebels who threatened Assad’s rule. From there, Putin deployed ground personnel, who fought alongside Syrian forces as well as fighters from the Lebanese terrorist group Hezbollah and Iran’s Islamic Revolutionary Guard Corps. Hundreds of thousands of Syrians lost their lives as a result. Many more were displaced.

The 2013 red-line episode not only enabled Assad to remain in power to perpetrate crimes against humanity. It also allowed Putin to cycle as many as 63,000 military personnel in and out of Syria over the years. They gained valuable battlefield experience, which they are now leveraging in Ukraine.

But the negative consequences didn’t end there. Once Putin moved into Syria, he deployed his formidable S-400 anti-aircraft systems to patrol the Syrian skies. This tied the hands of Israel, which has increasingly needed to conduct airstrikes in Syria, thanks to the Islamic Republic of Iran’s massive weapons-smuggling operation.

Iran has exploited the fog of war in Syria, using the battlefield to quietly move precision-guided munitions to Hezbollah in Lebanon. Never before has a nonstate actor acquired PGMs. There could be significant consequences if Hezbollah acquires enough of them. They would enable the terrorist group to strike strategic targets throughout Israel with deadly accuracy, and they could even evade Israel’s Iron Dome system. With enough PGMs, Hezbollah can one day wage a destructive war in Israel.

Expectedly, the Israelis have grown alarmed. Over the last several years, they have carried out thousands of attacks against Iranian and Hezbollah targets in Syria. For the Israelis, this is a matter of urgent national security. But to do so, they must deconflict with the Russian military. Indeed, as a result of the 2013 red-line episode, Israel needs Russia if it wishes to operate across its northeastern border.

In a bizarre twist, many of the same officials who failed to enforce Obama’s red line now serve the Biden administration. With zero self-awareness, they are excoriating Israel for not sufficiently aiding Ukraine. Somehow lost on them is that Israel cannot openly challenge Russia if it wishes to access Syrian airspace.

In another strange twist, the White House wants the oil-producing Arab states to make up for lost production resulting from sanctions on Russia. These states once yearned for the Obama administration to oust Assad. Instead, they watched in horror as Putin came to Assad’s rescue. Then they watched in disbelief as Washington inked a nuclear deal with Iran, yielding Tehran some $150 billion in sanctions relief. Significant chunks of that money helped buttress Assad’s regime.

As Biden lobbies our Arab allies for increased oil production, US and Iranian negotiators in Vienna are on the verge of yet another nuclear deal — with the Russians as the primary mediator, no less. The result will once again be the release of billions of dollars to bankroll Tehran and its proxies. Assad will once again be a beneficiary.

Biden himself recently warned of “consequences” if Moscow uses chemical weapons in Ukraine. For our allies in the Middle East, these threats ring as hollow today as they did in 2013.

Actions have consequences. So does inaction. Ten years later, our Middle East allies can attest to this. Ten years from now, our European allies may do the same.

Jonathan Schanzer is senior vice president for research at Foundation for Defense of Democracies. Enia Krivine is senior director of FDD’s Israel Program and National Security Network.

Twitter: @JSchanzer @EKrivine.