Small Russian incursion could pose major test for NATO, report warns

The report comes as NATO’s eastern flank faces growing drone threats, forcing allies to strengthen defenses against low-cost unmanned aircraft and border security risks.

Russia could test NATO’s Article 5 defense pledge with a limited Estonia incursion, raising fears of alliance division and wider conflict. Estonian soldiers march during a war memorial ceremony in Narva, Estonia, on Jan. 3, 2025. A limited Russian attack on the Estonian border city, directly across the Narva River from Russia, could challenge NATO’s ability to respond without Moscow committing to a broader invasion, according to a hypothetical scenario published by the U.S.-based Institute for the Study of War. (Rose Di Trolio/U.S. Army) Russia could test NATO’s bedrock collective defense pledge by sending a small number of troops to seize a sliver of Estonia, forcing allies to decide whether they want to risk taking it back, a new assessment says.

The aim would be “breaking the alliance by causing it to fail to activate and act appropriately on its Article 5 commitments,” the Institute for the Study of War said in an analysis published Monday. According to NATO’s founding charter, an attack on one member country is considered an attack on all of them. Invoking Article 5 is designed to trigger a collective military response by the other 31 countries in the bloc on behalf of the one under attack. “A number of NATO states will likely be very hesitant to invoke Article 5 over a limited incursion, fearing