I believe that the odds of a full-blown proxy war in Ukraine between the United States and Russia are now better than even and getting higher. Moscow believes it is already in a proxy war with the West, but it is wrong, at least in the following sense. Whereas Russian has been deeply involved in the violence in eastern Ukraine from its inception, Western military assistance to Kyiv has so far been minimal. That is likely to change if a stable ceasefire is not arranged in the next several weeks.

Since my last post, the fighting in eastern Ukraine has continued to escalate, with casualties mounting on both sides. Ukrainian forces are fighting hard, but the separatists have gained ground to the west of Donetsk and Horlivka and in the Debaltseve salient. Since the Minsk agreement was signed in September, the separatists have added some 500 square kilometers to the territory under their control. Military equipment and supplies continue to cross over from Russia, and NATO estimates that there are now some 1,000 Russian regulars and advisors in the conflict zone. While significantly lower than in August and September, that figure does not include the many “military tourists” among the separatist forces, including volunteers, criminals released from jail, and Russian servicemen “on vacation.”

The surge in armaments from Russia has allowed the separatists to carry out an offensive that has put several thousand Ukrainian troops in and around Debaltseve (the estimates I have seen are between 5,000 and 7,000) at risk of being trapped and then destroyed, captured, or used as leverage in negotiations over a new line of demarcation.

Another major development this week took place in Washington, where the administration is now considering an increase in military assistance to Kyiv, including provision of lethal defensive weapons. Republicans on the Hill, along with some prominent Democrats, have been pressing for increased military assistance to Kyiv for months. They were joined on Monday by eight former high-level officials, who issued a report advocating that Washington should provide Ukraine with $1 billion in direct military assistance, and another $1 billion in each of the next two years. They describe the nature of this assistance as follows.

Additional non-lethal assistance should include: counterbattery radars, unmanned aerial vehicles (UAVs), electronic counter-measures for use against opposing UAVs, secure communications capabilities, armored Humvees and medical support equipment. Lethal defensive military assistance should include light anti-armor missiles, given the large numbers of armored vehicles that the Russians have deployed in Donetsk and Luhansk and the abysmal condition of the Ukrainian military’s light anti-armor weapons.

The administration was already discussing increasing military assistance to Kyiv before the report was issued, as confirmed by a number of “leaks” to the press. In particular, the administration is said to be contemplating the delivery of Javelin anti-tank missiles to Ukraine. The “leaks” were no doubt intended as a warning to the Kremlin that it should order a halt to the offensive and negotiate a ceasefire or face a prolonged and debilitating war in Ukraine, but they also increase the likelihood that the administration will follow through with a surge in military assistance if the fighting continues to escalate.

The growing risk of an all-out proxy war, and the concomitant risk that it gets out of control and leads to a direct military conflict between Russia and NATO, led to a flurry of negotiations over the past week to bring a halt to the fighting, including a five-hour meeting between Putin, Merkel, and Holland in Moscow yesterday. Unfortunately, I think the current diplomatic offensive is more likely to fail than succeed for at least the following reasons: (1) Poroshenko is politically unable to accept a new line of demarcation farther to the west and north, and Moscow and its proxies are not going to accept a return to the Minsk line of demarcation; (2) Western governments continue to insist on full implementation of the Minsk agreement, which for reasons I laid out in earlier posts is not going to happen; and (3) Putin is not going to order a stop to the separatist offensive unless and until the separatists have achieved their immediate military objectives, if then.

If the separatists do attain their immediate objectives – which I believe are to drive the Ukrainians west from Donetsk and Horlivka and out of the Debaltseve salient – then I think there will be one final diplomatic opening, but only if the separatists manage to do so without a prolonged and bloody fight. I think that is unlikely. That is, I do not think the separatists will meet with success quickly or easily. There are a lot more Ukrainian troops in the salient than there were at the Donetsk airport, and they are likely to dig in and fight hard in another urban environment that favors the defenders.

Another possibility is that the separatists cut the Ukrainian troops in the salient off and hold them hostage in an effort to convince Kyiv to withdraw them and agree to a new line of demarcation. With Ukraine facing a truly acute financial and economic crisis (the hyrvnia is again in free fall, having fallen by 50% against the dollar in two days last week), and the separatists controlling the fate of thousands of Ukrainian servicemen, Kyiv might agree to withdraw and accept a new line of demarcation. But I think that is unlikely. Instead, Kyiv will probably try to turn Debaltseve into Ukraine’s Vukovar, a city that Serbia laid siege to at the beginning of the Croatia-Serbia war and eventually took, but only after months of intense fighting. Vukovar was a tactical victory but a strategic defeat for the Serbs.

If diplomatic efforts to negotiate a ceasefire fail, and if the fighting in Debaltseve and elsewhere continues for weeks or even months, the Obama administration will almost certainly increase military assistance to Ukraine. The U.S. has already been providing non-lethal equipment and training to the Ukrainians, and at the least it will ramp up the kinds of assistance already underway. But more likely than not the White House will decide to provide lethal weapons as well, which the Kremlin has more or less signaled is a redline for it.

It is important to appreciate, however, that a U.S. decision to supply lethal assistance to the Ukrainians would not have a significant impact on the battlefield for several months, at best. Given the intensity of the fighting, and particularly given the critical situation of the Ukrainian forces in and around Debaltseve, several months is a long time in the current conflict.

The likelihood of a diplomatic solution, either now or after the separatist take Debaltseve, would be greatly diminished by a public announcement at this point that Washington was significantly increasing military assistance to Ukraine. Were that to happen, I think the odds are better than even that Putin would order an open Russian assault on Ukraine directed at degrading the country’s war fighting capabilities, and/or that he would order a Russian invasion directed at establishing a land corridor to Crimea. There is also a risk that he would order Russian ground forces to invade from the north, enveloping the bulk of Ukrainian forces in the war zone. This kind of major escalation of Russian involvement, if it comes, would likely happen before any increase in Western military assistance made a difference on the battlefield.

To sum up, I doubt that the current diplomatic effort to arrive at a stable ceasefire will succeed, at which point much will depend on how things proceed on the battlefield. The critical issue is whether the separatists manage to trap a large number of Ukrainian troops in the Debaltseve salient. If they do, the separatists may offer to allow them to withdraw in exchange for agreement on a new demarcation line. Poroshenko would then have an extraordinarily difficult decision to make. I suspect that his decision would be to fight rather than withdraw given the mood in Kyiv.

It is a great deal easier to see how things can escalate at this point than to see how we get to a stable ceasefire and a frozen conflict, which I continue to believe is the least worst option for all parties.