Russian forces in Syria have fired upon Israel Air Force (IAF) aircraft on at least two different occasions, the Israeli daily Yedioth Ahronoth reported last week. Officials in Moscow unsurprisingly dismissed the report, but the possibility of Russian-Israeli clashes over Syria is actually more plausible than it may seem.

The skies above Syria are crowded, presenting ample opportunity for conflict. Syrian regime and Russian aircraft pound rebel positions, Israeli forces periodically target Syria’s Hezbollah ally, and the U.S. leads a coalition against the Islamic State flying both manned and unmanned missions.

Whether Russia has indeed fired upon Israeli aircraft is not as important, however, as the potential ramifications of Russian forces clashing with Israeli, U.S., or allied forces in the future. It appears that the question is not whether such an altercation will happen, but when.

Even in a perfect world, coordination between allies is difficult. The Turkish downing of a Russian Su-24 aircraft in November 2015 exemplifies the risks of various states pursuing their own military operations in close proximity. And given the cross-purposes at which the Russian and Syrian forces are working, an incident like those reported last week is a virtual inevitability.

While coordination between Russian and U.S. officials began in October to prevent conflict over Syria, reports indicate that the process has been far from perfect. American officials have stated that Russian planes have flown near a U.S. drone, and that they have had to redirect flights to avoid close encounters.

Chance encounters are one thing, and making efforts to prevent accidental run-ins is prudent. The problem arises when one party tries to test how far its adversary will bend. Indeed, the Kremlin has been consistently testing American restraint, ignoring the agreement on safety and separation established by the two nations.

In September 2015, soon after Moscow began its foray into Syria, President Obama said that a Russian presence there would not change U.S. strategy in countering the Islamic State. It is now clear that that has not been the case, particularly after the introduction of advanced Russian fighter aircraft and surface-to-air missile systems has forced U.S. military planners to modify their operations accordingly.

Israel confronts a more complex test. The IAF’s area of operation is situated in the air defense bubble established by Russia. The advanced S-400 air defense system that the Russians placed in Syria in November is of little use for their fight against militants, but it does complicate the calculus of Israeli aircraft operating nearby. Operationally, therefore, the Russian presence may limit freedom of movement for both the U.S.-led coalition and the IAF.

Understanding the Russian modus operandi is important not only to prevent escalation, but to confront the Kremlin’s strategic ambitions. This is not to suggest America or its allies should adopt a new Cold War mentality. But by ignoring the Kremlin’s actions that violate its own agreements with the U.S., Washington is ultimately establishing an environment where conflict becomes more likely, not less.

John Cappello is a senior fellow at the Foundation for Defense of Democracies focusing on military affairs and a former U.S. Air Force B-1 Lancer pilot.