Workers laying a cable beneath the Baltic Sea are on the front line in Lithuania's struggle for energy independence from Moscow.
Their adversary: the Russian Navy.
No shots have been fired, but construction crews laying the NordBalt cable linking Lithuania and Sweden have received unwelcome visits in the last month from Russian warships probing into the construction area in the Baltic state's exclusive economic zone.
Frustrated that its diplomatic protests have had no effect, NATO member Lithuania says it will consider legal action if the Russian moves don't stop.
"We've already informed our transatlantic partners of the issue and will continue raising it on other occasions both with the Russian Federation and other international partners," Foreign Minister Linas Linkevicius told RFE/FL.
"If similar incidents happen again, the possibility of employing international legal instruments against the Russian Federation will be considered," Linkevicius said.
Sweden, Lithuania's main partner in the NordBalt project, has also taken issue with what one member of its parliament called a "growing pattern" of Russian provocations.
The moves come amid a surge in Russian military activity near NATO member states since Moscow's takeover of Crimea and the start of the deadly conflict between government forces and Russian-backed separatists that has killed more than 6,100 people in eastern Ukraine since April 2014.
In the most recent incident, a vessel from the Russian Navy's Baltic Fleet entered Lithuania's exclusive economic zone on April 30 and headed toward a NordBalt construction ship managed by the Swedish-Swiss engineering conglomerate ABB, according to the Lithuanian Foreign Ministry.
It even tried to chase the construction ship away.
"The ALCEDO vessel chartered by ABB was asked by the Russian Navy to leave its position in Lithuania's exclusive economic zone, where it had a legitimate right to be, according to international law," Swedish Foreign Ministry spokesman Gabriel Wernstedt told RFE/RL.
"We have raised the issue with Russian authorities, as we've done when similar incidents have occurred," he said. "We take this very seriously."
Reducing Russia Reliance
The 450-kilometer underground NordBalt cable, approved by the Swedish and Lithuanian governments in 2013 and due to be completed in December, will be able to transmit up to 700 megawatts from Nybro in Sweden to the Lithuanian coastal city of Klaipeda.
With 14 overseas energy cables already in place, Sweden is an old hand.
But NordBalt is its first connection with one of the three Baltic states, which chafed under Moscow's rule for decades after World War II and joined NATO and the European Union after gaining independence in the Soviet breakup of 1991.
For Lithuania, NordBalt is a crucial tool for the painstaking task of reducing reliance on Russian energy -- a goal made more urgent by the Kremlin's interference in Ukraine, which has deepened concerns about its intentions in the region.
The country of 3.5 million currently imports 72 percent of its energy, of which 48 percent is bought from Russia.
The faceoff in the Baltic is far from the first obstacle to Lithuania's efforts to cut itself free.
In 2012, plans to build a nuclear power plant were rejected by voters in a consultative referendum -- an outcome the government blamed on Russian fearmongering.
That decision added impetus to a project for Lithuania's first liquefied natural gas (LNG) terminal, which was inaugurated in December.
A second international energy cable, linking Lithuania with Poland, is also scheduled to open later this year.
Hans Wallmark, a member of the Swedish parliament's foreign affairs committee, said the purpose of the Russian naval moves was clear. "The NordBalt provocations are part of a growing pattern of behavior by the Russians. They're establishing a set of different provocations," he said.
"Their goal is that to spread anxiety and dejection among their neighbors, but instead their actions will galvanize us," he said
Sweden, Finland, and the Baltic states of Estonia, Latvia, and Lithuania are by now accustomed to growing Russian military activity near their airspace and territorial waters.
This year, Latvia alone has registered some 50 approaches by Russian planes and 17 by Russian vessels, whereas five years ago it had around five air approaches and none by sea.
Last week, NATO Baltic Air Policing planes scrambled in response to two Russian planes near Baltic airspace. Operating close to another country's airspace or territorial water is not illegal, but air approaches are now policed by NATO planes.
In challenging civilian construction crews, Russia may be trying out a new tool in its arsenal.
"Let's hope that these are still incidents, not provocations," Linkevicius said. "However, the fact these incidents have been repeated several times recently, and that some of them recurred the day after a diplomatic note had been sent to the Russian side, raises our concern."
He said that Russia's navy has the right to conduct exercises in the Baltic Sea, but should "make sure that its military vessels don't create obstacles for the commercial vessels" in Lithuania's exclusive economic zone."
Russia's Foreign Ministry did not respond to a request for comment. But it has told Lithuania that Russian vessels in Lithuania's exclusive economic zone are simply protecting Russia's military exercise zones.
Estonian parliament member Indrek Tarand says diplomatic protest notes won't make Russia budge. "Russia only responds to shows of force, so Sweden, which has a bigger navy than the Baltic states, should stand up to the Russians and send a ship there," he said. "But a more permanent solution would be to have NATO policing of the sea just as we have in the air."
For a time, at least, the NordBalt construction crews may have some support.
Some ships that participated in Joint Warrior, a twice-yearly, British-led NATO exercise that ended on April 24, are now heading to the waters off Lithuania, Dutch commander Peter A.J. Bergen Henegouwen told the Swedish daily Goeteborgs-Posten.
The vessels' mission, however, is mine-hunting.