Russian combat operations on behalf of Syrian President Bashar al-Assad are likely to begin “soon,” three U.S. officials told The Daily Beast. And Russian drone flights to spot targets for potential airstrikes are already underway.

That concession by U.S. officials of growing Russian influence marks a shift from previous statements by officials who said they weren’t sure whether Russia intended to use force in Syria and enter into the country’s long and brutal civil war. There already are early signs that Russia plans to target moderate forces that threaten the Assad regime, not the self-proclaimed Islamic State, which has been the focus of a year-long U.S.-led air campaign.

And yet, the recent Russian moves, which threaten to undermine U.S.-led efforts over the last year, were met with hardly a shrug in some circles in Washington.

“There are not discussions happening here about what this means for U.S. influence on the war against ISIS,” one defense official told The Daily Beast.

That’s despite the fact that some unverified online videos indicate that the opening phases of such operations may have already begun.

A video posted September 15 to YouTube appears to show Russian military forces in tanks alongside Syrian forces in the Lattakia region, a traditional Assad stronghold that has come under threat from anti-regime forces.

Since last Friday, Moscow has sent two dozen additional fighter jets to Syria, bringing the total number in the country to 28. The same day, Defense Secretary Ash Carter spoke by phone to his Russian counterpart about what the Pentagon called “mechanisms for deconfliction,” a strong indication that Russia intended to conduct airstrikes in the same areas that U.S. forces and their coalition partners are now operating against ISIS.

After more than a year of U.S.-led airstrikes, the political and military situation in Syria appears to have reached a critical turning point, American officials and experts said. The U.S. campaign is effectively at a stalemate, Army Gen. Martin Dempsey, the outgoing chairman of the Joint Chiefs of Staff, has said. In recent weeks, as Assad lost ground and the Obama administration’s Syria policy came under withering criticism for failing to train and equip any significant rebel force, the Russians began moving military equipment, supplies, and troops into Syria.

The massing of Russian force would seem to add a new and potentially volatile element to the chaotic war, with the U.S. struggling to find allies on the ground or blunt the spread of ISIS, and U.S. military analysts accusing their senior officers of distorting intelligence to paint a rosier picture of the military situation.

U.S. officials said publicly they were concerned and keeping a channel of communication open to Moscow.

But privately, many seemed to welcome a Russian intervention if it alleviated the burden on the U.S. for fighting ISIS, even if that meant diminished American influence over how the war ends. Intervening on behalf of an ally bring its own challenges, they note.

The Russians “are going to inherit Assad’s mess,” a second defense official said. “I don’t know if they have looked at it from all possible angles.”

"Watching the Russians take the initiative is the most clear example yet of the complete abdication of U.S. leadership and responsibility in the region,” Christopher Harmer, a naval analyst at the Washington D.C.-based Institute for the Study of War, told The Daily Beast.

White House Press Secretary Josh Earnest, asked by reporters if the U.S. had any insights into Moscow’s endgame, replied, “To be blunt about it, no.”

State Department spokesman John Kirby told reporters Monday that the U.S. “concerns remain in place” about growing Russian moves in Syria.

Carter has not said a word about what many are calling an “inflection point” in Syria. On Monday afternoon, he held a Lean In event at the Pentagon with Facebook Chief Operating Officer Sheryl Sandberg, encouraging women in the military to support each other through small groups. Over the weekend, Secretary of State John Kerry repeated the Obama administration’s position that Assad must step down in order to forge a political settlement, but he remained open to postponing that departure to some unspecified date. Kerry has spoken with his Russian counterpart three times in the past week.

“We need to get to the negotiation,” Kerry over the weekend. “That is what we’re looking for and we hope Russia and Iran, and any other countries with influence, will help to bring about that. … Is Russia prepared to bring [Assad] to the table?”

German Foreign Minister Frank-Walter Steinmeier, while appearing with Kerry over the weekend in Berlin, said, “I strongly welcome the fact—and we’ve had reports here in Germany—about the growing military engagement of Russia in the region.”

The swiftness of Russian military escalation over the weekend was striking. In addition to the surveillance drones, Russia now has “Fencer” advanced-attack aircraft jets and “Frogfoot” jets for close air support among its arsenal, according to U.S. estimates.

Russia has also sent 16 helicopters, two surface-to-air missile batteries, nine T-90 tanks, and enough modular housing to hold 2,000 Russian troops, up by 500 in just a matter of hours. U.S. officials believe there are at least 500 Russian troops on the ground now, presumably to serve as advisers to Syrian forces on the front lines and help them launch more precise artillery strikes and support their ground forces from the air.

Precisely whom the Russians will be hitting with all that firepower—ISIS forces or other militants fighting to overthrow Assad, including those with whom the U.S. might try to align—remains unclear, U.S. officials told The Daily Beast, speaking on condition of anonymity to discuss intelligence and developing operations.

Some analysts said they anticipate Russia will seek to shore up the Syrian regime in the cities of Idlib and Aleppo, where Assad’s forces have lost territory in recent weeks. That suggests Russian forces would attack Syrian rebels as well as the terrorist organization al Nusra, both of which hold positions in those cities.

The Russian newspaper Novaya Gazeta cited one official who said military operations in Syria would be modeled after Moscow’s military occupation of eastern Ukraine and Crimea. The publication, which is generally critical of the Russian government, said missile strikes of grounds operations in concert with Syrian forces could begin prior to President Vladimir Putin’s address to the United Nations General Assembly in New York next week.

Meanwhile, Russia has been building an international alliance of its own. The Wall Street Journal reported that Russian and Iranian forces, as well as Hezbollah militants, have been coordinating their air operations and finding ways to defend Assad.

Meanwhile, Israeli Prime Minister Benjamin Netanyahu was in Moscow on Monday, along with two members of his general staff, to ensure his own military strategy in Syria will not be hindered by Putin’s. In the past few years, Israel has bombed numerous convoys of advanced weapons systems sent by Iran to Syria and destined for Hezbollah—now Russia’s active operational partner in Latakia. “My goal was to prevent misunderstandings between [Israel Defense Force] forces and Russian forces,” Netanyahu told journalists via telephone from Moscow. “We have established a mechanism to prevent such misunderstandings. This is very important for Israel’s security.” Netanyahu insisted that Israeli strikes on weapons systems must be allowed to proceed without Russian interdiction, and suggested that Putin had acceded to this condition.

Over the past year, the U.S. has conducted 5,358 strikes inside Iraq and Syria, targeting ISIS and in support of fighters like the Kurdish YPG, who have also fought the militant group that seeks to establish an Islamic regime in Syria and Iraq.

But for Assad, ISIS is not the only threat. Any so-called “moderate” foe that is seen as an alternative to his regime could be targeted by Russian forces, said Harmer, the military analyst. For that reason, he said, Russian forces would likely strike in Idlib and Aleppo first.

Russia needs “a pliant leader in Syria to maintain some semblance of control, who will still be dependent on Russia,” Harmer said. “Assad is the one puppet that fits all of that. The Syrian regime needs to kill the moderates so there is no alternative to them.”

— with additional reporting by Michael Weiss