The launching of coordinated air strikes by Russian and Turkish warplanes against Islamic State (ISIS) targets in northern Syria Wednesday has further exposed the crisis gripping Washington’s intervention in the war-ravaged Middle Eastern country, as well as the deepening contradictions plaguing the NATO alliance on the eve of Donald Trump’s inauguration as US president.

The bombing campaign struck targets around the Syrian town of al-Bab, the scene of bloody fighting between Turkish troops and ISIS militants over the past several weeks.

From a political standpoint, the joint action by Russia and Turkey, a member of the NATO alliance for the past 65 years, is unprecedented. It stands in stark contradiction to the anti-Moscow campaign being waged by Washington and its principal NATO allies, which has seen the cutting off of military-to-military ties, the imposition of sanctions, and the increasingly provocative deployment of thousands of US and other NATO troops on Russia’s western borders. Just last week, the US sent 3,000 soldiers into Poland, backed by tanks and artillery, while hundreds more US Marines have been dispatched to Norway.

Turkey’s collaboration with Russia represents a further challenge to the US-led alliance under conditions in which Trump has severely rattled its European members with recent statements describing NATO as “obsolete” and charging its members with not “taking care of terror” and not “paying what they’re supposed to pay.”

The joint air attack was carried out under the terms of a memorandum reached between the Russian and Turkish militaries the previous week, according to the Russian Defense Ministry.

The document, signed on January 12, was designed to prevent “incidents” between Turkish and Russian warplanes, as well as to prepare “joint operations ... in Syria to destroy international terrorist groups,” Lt. Gen. Sergei Rudoskoy said in a statement.

Russian-Turkish relations reached their nadir in November 2015 when Turkish fighter jets ambushed and shot down a Russian warplane carrying out airstrikes against Islamist fighters near the border between Turkey and Syria. The incident brought Turkey, and with it NATO, to the brink of war with nuclear-armed Russia. At that point, Turkey was serving as the main conduit for foreign fighters, weapons and other resources being poured into Syria to wage the US-orchestrated war for regime change, while Russia was intervening to prop up its principal Middle East ally, the government of Syrian President Bashar al-Assad.

In June of last year, Ankara sought to mend it relations with Moscow, which had retaliated for the shoot-down with economic sanctions. Relations grew closer in the wake of the abortive July 2016 military coup, which the government of President Recep Tayyip Erdogan blamed on the US and its allies.

The turning point in bilateral relations between Turkey and Russia came at the end of last year, with the Russian-backed Syrian army’s routing of the Western-backed, Al Qaeda-linked militias in their last urban stronghold of eastern Aleppo. Turkey joined with Russia in brokering a withdrawal of the last “rebels” from the area and a nationwide ceasefire, which continues to prevail in much of the country.

Washington was pointedly excluded from the negotiations surrounding both Aleppo and the ceasefire. Only at the last moment has Moscow invited the incoming Trump administration—over the objection of Syria’s other major ally, Iran—to participate in talks aimed at reaching a political settlement over the six-year-old war that are to convene in Astana, the capital of Kazakhstan, next week.

The joint Russian-Turkish airstrikes around al-Bab came in the wake of bitter protests by the Turkish government over the refusal of the US military to provide similar air support for Ankara’s troops in the area. The Pentagon’s reluctance stemmed from the conflicting aims pursued by Turkey, which sent its troops into Syria last August in what the Erdogan government dubbed “Operation Euphrates Shield.”

Ostensibly directed against ISIS, Ankara’s primary target was really the Syrian Kurdish Democratic Union Party (PYD) and its military wing, the People’s Protection Unit (YPG). The Turkish government views these groups as affiliates of the outlawed Kurdistan Workers’ Party (PKK), against which it has waged a protracted counterinsurgency campaign within Turkey itself. The offensive against ISIS-controlled al-Bab is aimed principally at preventing it from falling to the YPG and at blocking the linking up of eastern and western Kurdish enclaves along Turkey’s border.

For its part, Washington has utilized the YPG as its principal proxy ground force in the US attack on ISIS, sending in US special forces troops to arm, train and direct these Kurdish fighters.

The US refusal to back Turkish forces around al-Bab with airstrikes led to angry denunciations of Washington by the Turkish president, who charged that the US was supporting “terrorists” instead of its NATO ally. Ankara also began delaying approval for US flights out of the strategic Incirlik air base in southern Turkey and threatened to deny Washington and its allies access to the base altogether.

It was likely these threats, combined with the Turkish-Russian agreement to conduct joint strikes, that led the Pentagon to reverse its previous refusal to support Turkish forces and launch limited bombing runs around al-Bab as well this week.

This crowded and geostrategically tense battlefield is likely to grow even more dangerous following Trump’s ascension to the White House.

Trump has reportedly called for the Pentagon to come up with proposals to deal a decisive defeat to ISIS in Syria and Iraq within 90 days. Marine Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said on Wednesday that he would “present options to accelerate the campaign” against ISIS to retired general James Mattis, Trump’s incoming defense secretary.

Citing unnamed Pentagon officials, CNN reports that “The Defense Department is prepared to provide the new administration with military options to accelerate the war against ISIS in Syria that could send additional US troops into direct combat.”

“One option would put hundreds, if not thousands, of additional US troops into a combat role as part of the fight to take Raqqa,” the Islamic State’s Syrian “capital,” according to the television news network. “... in the coming months, the Pentagon could put several US brigade-sized combat teams on the ground, each team perhaps as many as 4,000 troops.”

Plans are also reportedly being drawn up to escalate military provocations against Iran, which Mattis, in testimony before the Senate, described as the “biggest destabilizing force in the Middle East,” adding that the Trump administration must “checkmate Iran’s goal for regional hegemony.”

There is every indication, Trump’s rhetoric about improving relations with Moscow notwithstanding, that US imperialism is preparing for another eruption of militarism in the Middle East that will pose an ever greater threat of spilling over into a new world war.