Since Russia invaded Ukraine, many have called for Ukraine’s skies to be “closed.” This translates to the enforcement of a no-fly zone over Ukraine. The demand does not refer to commercial airlines, since nearly all international carriers have canceled flights to and from the country for safety concerns. The new request pertains to the enforcement of a no-fly zone over Ukraine for military aircraft.

To implement a no-fly zone, NATO countries would first have to establish that an airspace, in this case, Ukrainian, is off-limits to military aircraft. Enforcing this policy would require NATO aircraft to patrol the area and shoot down any plane entering Ukrainian airspace. Supporters of Ukraine see the no-fly zone as a way for western countries to defend the country while still staying out of the conflict, but its enforcement would compel NATO-member states to join the war. If NATO were to shoot down a single Russian plane, then it would almost certainly lead to a declaration of war between Russia and the West.

The West has made it clear they unequivocally support Ukraine, but a direct military conflict with Russia is a nonstarter. So instead, European nations and the US have levied a flurry of sanctions against Putin and other oligarchs which have so far crippled the Russian economy but not forced the withdrawal of troops from Ukraine.

Despite NATO’s reluctance to close Ukraine’s airspace, Poland, a NATO member, has sought to help Ukraine defend its airspace through other means. This past week the country offered to transfer its MIG fighter jets to the US, free of charge, to donate to Ukraine. This seemed like a logical compromise as Ukrainian pilots are already familiar with the planes eliminating the need for additional training. But US officials rejected the offer and admonished Poland for making the proposal. The move would likely elicit a retaliation from Russia, which both Poland and the US want to avoid.

As the war in Ukraine evolves, the West will likely change its stance on military and economic support. For now, the West is trying to toe a line of supporting Ukraine while not provoking Putin. Finding the right balance will prove to be a difficult task; one misstep could trigger WWIII.