With Tuesday’s passing of the deadline under a UN peace plan for the withdrawal of army troops from Syria’s major population centers, Washington and its allies have escalated their threats of intervention in the Middle Eastern country.

Under the six-point plan drafted by former UN Secretary General Kofi Annan, Syrian troops and heavy weapons, including tanks, were to have been removed from towns and villages by April 10 as the prelude to a ceasefire by both government forces and the Western-backed armed opposition forces 48 hours later.

Endorsed by the Security Council as well as the Arab League and accepted by the government of President Bashar al-Assad, it is becoming increasingly apparent that the Annan plan, as far as Washington, the Western European powers, Turkey and the reactionary Gulf oil sheikdoms are concerned, represented merely a ploy aimed at legitimizing imperialist intervention.

Reports in the major media have been filled with charges that the Assad government has “defied” the Annan plan and is continuing alleged atrocities against civilians, seemingly without provocation. Wildly inflated estimates of the number killed provided by opposition-controlled—and Saudi funded—outfits like the British-based Syrian Observatory for Human Rights are reported as fact, while the deaths of Syrian soldiers and police are barely mentioned.

In a letter to the UN Security Council Tuesday, Annan said that he was “gravely concerned at the course of events” in Syria.

He said that “credible reports indicate that … the Syrian armed forces have conducted rolling military operations in population centers, characterized by troop movements into towns supported by artillery fire. While some troops and heavy weapons have been withdrawn from some localities, this appears to be often limited to a repositioning of heavy weapons that keeps cities within firing range.”

The ex-UN secretary general rejected out of hand an appeal made by the Syrian government on April 8 for the UN to secure written guarantees from the armed groups such as the Free Syrian Army that they would halt terrorist violence and from countries in the region that they would stop financing and arming these factions.

At a “Friends of Syria” conference in Istanbul, held on April 1—one week after the Assad government signed on to the Annan plan—Saudi Arabia and Qatar announced that they were not only arming the “rebels”, but would be putting them on their payroll. The US and Britain, meanwhile, have pledged “non-lethal” support, including sophisticated communications gear, night-vision goggles and intelligence that can be used to target government forces.

Despite these clear efforts to escalate the civil war in Syria, Annan described the requests from the Assad government as “ex post facto requirements that are not part of the six-point plan that they agreed to implement.”

Earlier on Tuesday, Russian Foreign Minister Sergei Lavrov announced that the Syrian government was no longer demanding written guarantees from the armed opposition groups, but merely assurances from Annan that the groups backed by the West together with Saudi Arabia and Qatar would cease armed actions and that their foreign sponsors would support the peace plan.

Lavrov spoke after two days of talks with Syrian Foreign Minister Walid al-Moallem in Moscow. He said that the Assad government “could have been more active and decisive” in implementing the Annan plan, but added that Damascus remained committed to complying with its requirements.

Russia, along with China, had vetoed two earlier Security Council resolutions because of their failure to mention the armed attacks of groups like the Free Syrian Army and their demands for the ouster of Assad. Having acquiesced to the US-NATO war for regime-change in Libya by failing to exercise their veto power, Russia and China forfeited their own interests in the oil-rich country in a war that claimed tens of thousands of lives.

Having come forward as a broker for the Annan plan, Russia has opened itself up to increasing pressure from the Western powers to accept UN-backed action against Syria if the Assad government fails to abide by the plan’s terms. With Syria representing a major trading partner and offering Moscow its only warm water port outside Russia, the Russian government confronts a deepening crisis over events unfolding in the country.

Two incidents Monday involving Syrian troops firing across the country’s borders have heightened tensions and raised the specter of the Western-stoked civil war turning into a regional conflagration.

In the first incident, Syrian troops were in pursuit of an armed group that attacked a military checkpoint near the Turkish border, killing six soldiers. The assailants then fled into Turkey. The gunfire wounded five people—three Syrian refugees and two Turks—at a refugee camp next to the Oncupinar border post near the provincial center of Kilis in Turkey. According to one report, Syrian refugees ran out of the camp to come to the aid of the fleeing gunmen.

In the second incident, a Lebanese television cameraman was shot dead by Syrian troops as he was filming along the border with Syria. Syria’s state news agency SANA said that the gunfire was the result of an “armed terrorist group” staging a cross-border raid against a Syrian border post.

Turkish Prime Minister Recep Tayyip Erdogan denounced the first clash as a “clear violation of the border.” He added, “Obviously we will take the necessary measures.”

The pro-government newspaper Zaman reported Monday that the Erdogan government was considering the invocation of a 1998 agreement with Damascus to legitimize an armed intervention in Syria. The accord included Syria’s pledge not to undermine Turkey’s security.

The Turkish media reported that Ankara is “finalizing plans” to impose a “buffer zone” or “humanitarian corridor” by its militarily seizing Syrian territory and using it to house refugees and train armed anti-government groups.

Syrian Foreign Minister Moallem countered the shrill reaction from Ankara, stressing that Turkey was itself fomenting violence inside Syria by “hosting gunmen, giving them training camps, allowing them to smuggle weapons.” The nominal head of the Free Syrian Army, a hodgepodge of locally based militias, has made his headquarters in Turkey, near the Syrian border.

In response to threats of a Turkish imposed buffer zone on Syrian territory, Moallem stated, “Syria is a sovereign state and has the right to defend its sovereignty against any violation of this sovereignty.”

The United States described itself as “absolutely outraged” by the firing into Turkey. Ominously, State Department spokesperson Victoria Nuland suggested that Turkey could invoke mutual defense provisions of the NATO treaty over the border incident, clearing the way for a US-Western European intervention. “I would not be surprised if the Turks do raise this in Brussels,” she said.

One reporter at the State Department asked Nuland how what had happened on the Syrian-Turkish border was any different from the kind of actions US occupation troops regularly engage in on the border between Afghanistan and Pakistan. Nuland insisted that the comparison was “apples and oranges”, stressing that the US had “protocols” with Pakistan and falsely alleging that the Syrian forces were chasing “innocents”.

The growing constituency for imperialist intervention in Syria within the US ruling elite was reflected in back-to-back editorials in the Washington Post and the New York Times proclaiming the failure of the Annan plan and the inevitability of another war.

The Post declared: “The inescapable reality is that Mr. Assad will go on killing unless and until he is faced with a more formidable military opposition. That is why the shortest way to the end of the Syrian crisis is the one Mr. Obama is resisting: military support for the opposition and, if necessary, intervention by NATO.”

The Times, only slightly more circumspect, demanded that the United Nations Security Council “take tough and unified action against Mr. Assad and his forces,” and that Russia and China “stop protecting his brutal regime”, i.e., allow the US, Britain and France to ram through a resolution authorizing a Libya-style war for regime-change.

Popular sentiment in the United States, however, is wildly at odds with this increasing support for war within the political establishment. A survey, conducted by the Pew Research Center late last month, found that only 25 percent of the public believes that Washington should intervene in Syria, while roughly two-thirds (64 percent) oppose such an intervention.