Ret. Gen. David Petraeus testified before Congress on Russia’ recent actions in Syria. (AP)

In Syria, one of Russian President Vladimir Putin’s basic objectives is “to keep that naval base [at Tartus] and indeed to keep a base [in Latakia Province]” along the Mediterranean coast that “has been challenged increasingly in recent months by [the Islamic State] and then by other opposition forces.”

Putin also is concerned about Chechens fighting in Syria. “There’s a worry, of course, they’ll go back, presumably [to Russia], and be more effective” opposing Moscow.

Those are views voiced last Tuesday by David H. Petraeus, the retired Army general and former director of the Central Intelligence Agency, during a multi-hour tutorial on the Middle East at a Senate Armed Services Committee hearing.

Sen. Jack Reed (R.I.), the panel’s ranking Democrat, called Petraeus’s testimony “insightful and thought-provoking.”

Petraeus’s statements on Russia and Syria didn’t get much attention, but they need to be considered.

For example, while saying Putin is “playing his hand tactically quite effectively,” Petraeus, who works for the New York global investment firm KKR, raised questions about the Kremlin’s continued ability to finance its actions in Ukraine, Syria and Eastern Europe.

“At the end of the day, Vladimir Putin is going to run out of foreign reserves,” Petraeus said. “He’s probably got $200 billion or so left; he will burn through those in the course of the next two years. And if the sanctions [by the United States, European Union and others over Ukraine] are still imposed at that time, he and the companies that have debt coming due — he’s running a very large fiscal deficit — are not going to be able to go to the world markets and get money to finance their government operations.”

Although Petraeus thinks Putin “has actually a limited window of a couple of years to continue provocative actions,” he cautioned, “we have to be very careful during this time, when he could actually lash out and be even more dangerous than he has been.”

Russia’s buildup of the port at Tartus, Moscow’s main entry for arms shipments to the Syrian government, and construction at an older air base where more than 20 fighters and surveillance aircraft are stationed, did not bother Petraeus.

But, he warned, “If they [the Russians] really enter the fight on the side of [Syrian President Bashar al-Assad], rather than just sort of protecting . . . this coastal enclave that matters to them strategically, geostrategically, then we’re going to see real complications.”

Petraeus supported military-to-military talks with Moscow, saying they could “make sure that nothing goes bump in the night, that there is not an operation carried out by either side that is misconstrued by the other . . . and ends up in shooting where there doesn’t need to be shooting.”

He added, “You don’t want to be in direct conflict . . . Russia is an important power. It has carried out very provocative actions. It doesn’t mean that we need to be provocative in return. But we do need to be firm in return; we do need to establish what [are] unacceptable actions.”

That, hopefully, is what President Obama made clear to Putin in their talk at the United Nations on Monday.

Right now, Putin “wants to make sure that Bashar (al-Assad) is not thrown under the bus by either other regime members or perhaps even Iran, until at least he [Putin] has some better sense of the way forward,” Petraeus said.

In that sense, the Russian leader is no different from Obama or Petraeus, who said, “We should not rush to oust Assad without an understanding of what will follow him.”

Petraeus was critical of the Obama administration’s Syrian policy, saying, “elements of the right strategy are in place, but several are under-resourced, while others are missing.”

He called for Obama to take two steps that could involve the U.S. having direct military confrontations with Assad’s forces: “Tell Assad that the use of barrel bombs must end — and that if they continue, we will stop the Syrian air force from flying,” Petraeus said.

He also voiced support for “the establishment of enclaves in Syria protected by coalition air power,” safe zones where “a moderate Sunni force could be supported and where additional forces could be trained, internally displaced persons could find refuge, and the Syrian opposition could organize.”

He acknowledged, however, that “There’s nothing safe about a safe zone, unless you’re going to defend it . . . So we would have to invest in supporting that zone.”

Petraeus conceded the latter could involve putting “on the ground some [U.S.] advisers or support elements . . . in the same way that we have them on the ground in Iraq.” But in Iraq, the U.S. troops have been invited by the Baghdad government. There would be no such governmental invitation in Syria, where American forces would be supporting anti-Assad elements.

That is why U.S. military actions are directed solely against the Islamic State or other terrorist groups — acting under the post-9/11 congressional authorization to use force against terrorists. There is no such legal authorization to use U.S. military units against Syria.

Petraeus makes one other powerful point — some 70 percent of the Syrian men, women and children are Sunni.

“The central problem in Syria is that Sunni Arabs will not be willing partners against the Islamic State unless we commit to protect them and the broader Syrian population against all enemies, not just ISIS. That means protecting them from the unrestricted warfare being waged against them by Bashar al Assad — especially by his air force and its use of barrel bombs.”

Under U.S. law, the president would need something more from Congress to carry on the operations that Petraeus says would be a “very complicated military activity.”