The country is growing accustomed to debate about the use of drone aircraft in military surveillance and strikes. Should the U.S., as it has under President Barack Obama, be leaning more heavily on the use of the remote-controlled airplanes to hunt and kill terrorists — including American citizens?

In The New York Times this weekend, Scott Shane points to another debate about drones, one that is inevitable as other countries hurry to catch up to America in their development of the weapons. What should the U.S. do when another country starts to use drones the way it has in Afghanistan, Pakistan, Yemen, and elsewhere?

Eventually, the United States will face a military adversary or terrorist group armed with drones, military analysts say. But what the short-run hazard experts foresee is not an attack on the United States, which faces no enemies with significant combat drone capabilities, but the political and legal challenges posed when another country follows the American example. The Bush administration, and even more aggressively the Obama administration, embraced an extraordinary principle: that the United States can send this robotic weapon over borders to kill perceived enemies, even American citizens, who are viewed as a threat.

“Is this the world we want to live in?” asks Micah Zenko, a fellow at the Council on Foreign Relations. “Because we’re creating it.”

The challenge could be faced along any number of restive borders (in Kashmir, or in northern Mexico) or against breakaway elements within a country (the Uighurs in Xinjiang Province, in China, perhaps, or in Chechnya). And the United States won't be able to say much in protest without sounding hypocritical. “The problem is that we’re creating an international norm,” Dennis M. Gormley, a senior research fellow at the University of Pittsburgh tells Shane. The U.S. position is that it can strike across borders to kill terrorists — Anwar al-Awlaki, for instance — when they are even suspected of planning attacks. How could this country now tell other military powers they can't do the same. So far, the only other country to have made a strike outside the Afghanistan war zone, where British drones are active, is Israel, which used an unmanned vehicle to attack suspected militants in Gaza.

As the Obama administration has dramatically ramped up drone attacks, the country may face a new arms race. It may also eventually have to debate the underlying question that is now being avoided: does this type of warfare really work? At 10 civilians killed for every terrorist, as the Brookings Institution estimates, the attacks may be undermining any effort to win over the proverbial hearts and minds. But for the U.S., to kill an al-Awlaki, that may prove to be worth the cost. How will we respond when another country starts making similar, cold calculations?