(Bloomberg) — The North Atlantic Treaty Organization has an increasingly tricky problem in its backyard: how to confront the spillover from Russia’s war without sparking further escalation.

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As Ukraine reaps a bumper harvest, Russia is targeting the export routes that run from the ports around Odesa. That’s forcing grain ships on a new path that hugs the Romanian coastline and bringing the threat of attacks closer and closer to NATO’s shores.

Romanian radar detected a breach of its territory last weekend, the latest in a string of such incidents, while Bulgaria next door has found drone debris on its soil. Off shore, drifting sea mines and GPS-jamming that risks marine collisions are pushing the 31-member alliance into taking a view.

For now, it is inclined to see the incidents as mishaps. Even so, the subject is expected to be raised at a meeting of defense ministers in Brussels next week, according to a NATO diplomat, who asked not be named when discussing confidential information.

The head of the Romanian armed forces, Daniel Petrescu, echoed NATO Secretary General Jens Stoltenberg’s reading of the events when last week he warned of a need to be vigilant against “accidents.”

“Russia’s war and strikes close to Romanian borders are reckless and are destabilizing,” Stoltenberg had told reporters in Kyiv, but emphasized that the drone debris didn’t appear to result from intentional targeting.

Last year, a missile that struck Polish territory and killed two people had briefly raised alarm within NATO, whose collective defense arrangements mean member states come to each others’ aid if attacked. Investigators later found that it was caused by a Ukrainian missile.

Mode of Escalation

The sheer number of cases may suggest a less innocent explanation, according to Iulia Joja, the director of the Black Sea program for the Washington-based Middle East Institute think tank.

“This is unfortunately the Russian fashion of escalation,” she said of the incidents, which number at least a dozen. “They try and probe our limits, our so-called red lines, and if they perceive our response as weak, they probe further.”

Russia is keen to avoid sinking cargo ships openly, according to a report from British intelligence published Wednesday, and will instead falsely blame Ukraine for any attacks against civilian vessels in the Black Sea.

How Russia Is Choking Ukraine’s Vital Grain Exports: QuickTake

For more than two months over the summer, Russia declared a section of the Black Sea within Bulgaria’s exclusive economic zone to be dangerous for navigation, hindering cargo transit, gas exploration and other commercial activity there.

Now incidents are picking up as Kremlin forces target Kyiv’s use of alternative river, rail and road routes to ship its crops after Moscow exited the Black Sea commerce deal in July. The current workaround is both more expensive and puts the shipments, as well as anything targeting them, within reach of Ukraine’s NATO neighbors.

Cargoes tend to be taken over land to the Danube basin before being placed onto river boats, which are smaller than the vessels designed to go by sea. Their size forces them nearer to the shore — never mind the fact that boats traveling further out can no longer count on safe passage.

Still, at least 10 cargo ships have completed the journey through deeper waters. It is a risky one: the British intelligence report said that since July, Russia has destroyed enough grain to feed more than 1.3 million people for a year.

The prospect of Russia returning to a deal with Ukraine remains remote as it has a strong incentive to erode Kyiv’s economy and wear it down long-term, according to Sidharth Kaushal, a research fellow in sea power at the Royal United Services Institute think tank. The de-facto blockade means tensions are likely to stay elevated, especially while Ukraine is launching counter-attacks on Russian assets in Crimea.

NATO allies are trying to ascertain more information about the drone debris incidents and are warning Moscow of the risks of escalation, according to one senior US government official. Alongside other provocations, the recent incidents are starting to raise questions about whether the bloc’s assets in the Black Sea are sufficient to deter spillover, let alone an actual assault.

The alliance has been slow to match Russia in prioritizing defense around the Black Sea and only established battle groups in Romania and Bulgaria last year. Those complement the so-called tripwire units set up in Poland and the Baltics back in 2014.

Even now it is catching up, NATO faces a foe that’s particularly assertive in the Black Sea theater, according to one senior Eastern European diplomat, leaving allies feeling options that won’t inflame tensions are limited. By contrast with the Arctic and Baltic, where Russia is enveloped by NATO countries, of the six countries bordering the Black Sea only Romania, Bulgaria and Turkey are members of the alliance.

The US has pledged F-16s to Romania to help with air policing while allies are looking at what more can be done with counter-drone technology, the US official said.

Bulgaria is stepping up its own naval security, last month launching a tender to buy anti-ship missiles for its coast guard, while Romania has increased its forces in the Danube Delta area bordering Ukraine, according to an official. Although Romania already has more than 100 radars installed, it must adapt to detect Russian drones which fly at very low altitudes, the official said.

As for Ukrainian strikes on Russia, a French official told Bloomberg that allies need to be prepared for an erratic response by hostile forces in the region, describing these attacks as akin to a mosquito biting non-stop.

–With assistance from Alberto Nardelli, Andra Timu, Selcan Hacaoglu, Olesia Safronova, Áine Quinn and Ania Nussbaum.

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