A month after the Pentagon’s new National Defense Strategy named Russia as a strategic geopolitical competitor, an incident in Syria had to the potential to bring tensions to a new level. Just two weeks ago, at least five Russian mercenaries died from U.S. airstrikes in Syria.

Surprisingly, it appears that the death of Russians at American hands is passing by without a response from either country. A spokesperson for President Vladimir Putin deflected questions about the strikes stating, “We don’t have information about other Russians who might be in Syria. I advise you to contact the defense ministry.” The United States likewise showed little concern, completely ignoring the Russian deaths in the Pentagon press release.

The reason this incident did not elicit an even mild reaction from either country is puzzling. It is true that the men killed were Russian mercenaries, however, that does not fully negate the fact that Russians were killed by Americans in an armed conflict. It is entirely plausible that such an incident would escalate the nascent conflict between the two countries in dangerous ways. To argue otherwise would ignore the serious tensions that have strained U.S.-Russian relations over the past decade.

And, while the relative calm with which both sides have approached this incident is welcome, ignoring these deaths might make them appear acceptable by implying that it is permissible to kill citizens of the rival country. Additionally, the lack of reaction raises the question of what would constitute an event that warranted a response from either government. Without a reaction from either side advising against future military action, what is acceptable and to what extent remains dangerously ambiguous.

Between two countries that already have high tensions, it is alarming that the deaths of Russian mercenaries at the hands of American airstrikes are simply being passed as nothing special. So long as neither country sets a limit as to what is acceptable and what is not, the chances of a misstep with significant consequences remain high.