Western intelligence agencies are increasingly concerned that Russia may be preparing a limited hybrid operation targeting NATO's eastern flank, potentially involving the Baltic states or Poland.
Such a move, officials believe, could be an attempt to test the alliance's unity as the war in Ukraine enters a new phase.
According to reporting by The Guardian, intelligence officials from two NATO countries have warned that Moscow is considering a "provocation" rather than a full-scale military attack.
Latvian intelligence this week said it had detected indications that Russia was preparing military provocations against the Baltic states or Poland, while a senior political source from another NATO member said President Vladimir Putin could be seeking to test the alliance's resolve by targeting some of its smallest members.
Polish Prime Minister Donald Tusk also acknowledged growing concerns following a summit of eastern NATO members in Gdansk, warning that the regional security environment had become increasingly unstable and that further escalation could be expected in the coming weeks and months.
Officials stress that Russia is unlikely to open a second conventional front while its forces remain heavily committed in Ukraine.
Instead, analysts believe Moscow could resort to hybrid tactics, including drone incursions, missile launches, sabotage operations, cyberattacks or disinformation campaigns designed to intimidate NATO governments and undermine public support for continued military assistance to Kyiv.
The warnings come as Ukraine has significantly expanded its long-range strike capabilities, carrying out increasingly sophisticated drone attacks deep inside Russian territory.
Recent Ukrainian operations reportedly targeted infrastructure around Moscow and St. Petersburg, increasing pressure on the Kremlin and raising concerns among Western officials that Russia could seek to retaliate outside Ukraine.
Russia has previously demonstrated a willingness to conduct hybrid operations across Europe. In 2024, European investigators linked Russian intelligence operatives to a series of parcel bomb incidents involving DHL logistics shipments in Poland, Germany and the United Kingdom.
The attacks, which involved incendiary devices concealed inside cargo parcels, were widely viewed as a coordinated sabotage campaign intended to disrupt European transport networks.
Poland has also experienced repeated violations of its airspace. Last year, NATO aircraft were scrambled after multiple Russian decoy drones crossed into Polish territory during a large-scale missile attack on Ukraine, prompting authorities to issue public shelter warnings in several eastern provinces.
European security officials have also attributed numerous cyberattacks, GPS jamming incidents affecting civilian aviation over the Baltic Sea, and coordinated disinformation campaigns to Russian state or state-backed actors.
In recent years, undersea telecommunications cables and critical infrastructure in the Baltic region have likewise been subjected to suspicious damage, prompting increased NATO surveillance and maritime patrols.
Military analysts caution that hybrid attacks are designed to remain below the threshold of conventional warfare while creating political uncertainty and testing NATO's collective response under Article 5 of the alliance's treaty.
Keir Giles, a Russia specialist at Chatham House, told The Guardian that Moscow is likely searching for ways to alter the strategic balance as its offensive in Ukraine loses momentum.
Rather than accepting battlefield setbacks, he said, Russia may seek "horizontal escalation" by creating crises elsewhere in Europe.
NATO leaders are expected to discuss the growing hybrid threat at their upcoming summit in Ankara, where strengthening the alliance's eastern defenses and improving resilience against sabotage, cyber operations and disinformation are likely to feature prominently on the agenda.