WARSAW — Poland on Thursday said it had detained nine foreigners accused of spying for Russia and preparing sabotage operations to disrupt the flow of Western arms into neighboring Ukraine.
The presence in Poland, a member of NATO, of a Russian spy ring intent on damaging Polish infrastructure used to transport weapons and ammunition to Ukraine would signal a risky escalation by Moscow, which has so far avoided striking at targets inside alliance territory.
Mariusz Kaminski, the Polish interior minister, announced the dismantling of what he said was a major Russia espionage network a day after a visit to Warsaw, Poland’s capital, by the C.I.A. director, William J. Burns, who has played a key role in coordinating the delivery of Western-supplied arms to Ukraine by train and road from Poland.
“The suspects conducted intelligence activities against Poland and prepared acts of sabotage at the request of Russian intelligence,” Mr. Kaminski told journalists in Warsaw. The planned sabotage, he said, was “aimed at paralyzing the supply of equipment, weapons and aid to Ukraine.”
Poland, a stalwart ally of the United States and one of Europe’s most robust supporters of Ukraine, is the main transit route for weapons and ammunition provided by the United States and other countries to help Ukraine defend itself against Russia’s military onslaught.
Neither Poland nor the United States gave any details of the C.I.A. director’s talks Wednesday with the Polish president, Andrzej Duda, and Jacek Siewiera, the head of Poland’s National Security Bureau. A brief statement issued by the Polish presidency said only that they had discussed “the general security situation in the context of recent events.”
Accusing Western nations of “pumping up” Ukraine with weapons, Russia last year declared arms convoys “a legitimate military target,” but so far has refrained from striking railway lines or roads into Ukraine from eastern Poland, whose territory is covered by the NATO alliance’s commitment to collective security.
During the Soviet war in Afghanistan from 1979 to 1989, the K.G.B. and the G.R.U., the Soviet military’s intelligence agency, organized regular sabotage missions inside Pakistan to try to prevent weapons from the United States, China and other countries from crossing into Afghanistan. Soviet and Afghan government warplanes also bombed Pakistan’s border region, a haven for mujahedeen fighters backed and armed by the United States.
Bombastic commentators on Russian state television have often called for strikes inside Poland’s border with Ukraine, but their threats are generally dismissed as part of a Russian campaign to scare off Western support for Ukraine.
Mr. Kaminski, who oversees Poland’s security services, said six of the nine had been detained in an initial round of arrests by Poland’s Internal Security Agency, or A.B.W., and had been formally charged with espionage. The three others, arrested on Wednesday, were still awaiting formal charges, he said.
He said that none of the people arrested were Polish, and that all of them had come “from across the eastern border.” He did not specify their nationalities. Poland borders Ukraine and Russia’s client state Belarus in the east and the Russia territory of Kaliningrad in the north.
They had been monitoring railway lines with cameras and other equipment and carrying out other hostile tasks in return for regular payment from Russia’s intelligence services, he said. The A.B.W., Mr. Kaminski said, had found cameras, electronic equipment and GPS transmitters intended for mounting on weapons transports to Ukraine.
A Polish radio station, RMF-FM, reported earlier that cameras had been found near an airport in the eastern city of Rzeszow, a major logistical hub for military and humanitarian aid to Ukraine. The cameras, the radio station said, recorded movements on railway tracks near the airport and transmitted images.
Mr. Kaminski said the people had also received orders from Russia “to carry out propaganda activities in order to destabilize Polish-Ukrainian relations, incite and arouse hostile sentiments toward NATO countries in Poland, and to attack the Polish government’s policy toward Ukraine.”
Poland, though bitterly polarized between supporters and opponents of the governing Law and Justice party, has mostly united behind Ukraine. But some far-right groups, angling for support ahead of national elections later this year, have sought, so far with little success, to stir public hostility to Ukrainian refugees, more than 1.5 million of whom are now living in Poland, and have demanded an end to military aid.
Anti-Ukrainian sentiment was once strong among many Polish nationalists, angry that Ukraine has never fully acknowledged or apologized for the massacre of Poles by Ukrainian nationalists before and during World War II in territory that was formerly part of Poland.
Since Russia launched its full-scale invasion of Ukraine last February, however, hostility to Ukraine on the right has largely faded, replaced by much stronger and deeper hostility toward Russia, which has repeatedly attacked Poland in the past.