It should be a moment of celebration for Europeans working to achieve energy independence from Russia: On Saturday, natural gas is set to start flowing through Baltic Pipe, the only new natural gas pipeline to come online in Europe in decades.

Started in 2018, the brainchild of Poland and supported by the European Union, Baltic Pipe will bring gas from the bountiful energy riches of Norway to Central Europe, through the Polish coast. The gas could then flow through overland pipelines to other European Union countries in the region.

But overshadowing its opening is the suspected sabotage this week on the two Nord Stream pipelines. The devastation of the twin undersea arteries has raised fresh concerns about the potential vulnerability of the newest gas link running through the Baltic Sea.

Poland has envisioned Baltic Pipe since the 1990s and considers it a key step to ending its dependence on Russian gas — which hasn’t been flowing to the country since Russia cut off supplies in April.

“Today we are entering a new era, an era of energy sovereignty, of energy freedom and of enhanced security,” Mateusz Morawiecki, the prime minister of Poland, said at a ceremony on Tuesday.

But fears that this freedom could be jeopardized have grown in the days since the Nord Stream pipes began gushing methane to the surface. Leaders from Europe and the Kremlin have called the leaks “sabotage” so sophisticated that only a state actor would have been capable of carrying them out.

The damage poses an increased risk to the overall energy supply in Europe, which is already scrambling to wean itself from decades of reliance on fossil fuels from Russia. It also raises fears of a significant escalation in the proxy energy war between Moscow and the West since Russia invaded Ukraine in February, analysts said.

“The risk to near-term gas flows has risen sharply on fears that further sabotage could occur on critical gas import pipelines,” said Fitch Solutions, a market research firm, citing Baltic Pipe.

Experts say the new pipeline, which can carry up to 10 billion cubic meters per year, or enough to replace the amount of natural gas that Poland had received from Russia, is part of a wider effort by the European Union to diversify the energy infrastructure, especially in Central and Eastern Europe.

The pipeline, along with new terminals in Poland and Latvia to receive shipments of liquefied natural gas and new regulations to increase interdependency and reduce barriers, is part of Europe’s broader strategy to loosen the energy monopoly once held by Russian state enterprises like Gazprom, said Benjamin L. Schmitt, a research associate at Harvard and former European energy security adviser at the U.S. State Department.

But even the most robust energy networks can function only if they are secured, he added. “Those are all key components to security of supply and a well-functioning market, but if you don’t have physical and cybersecurity to back that market up, you are going to end up with what are effectively statues,” he said.

Baltic Pipe is the third major gas line running under the Baltic Sea, along with the now ruptured Nord Stream lines. The Polish pipeline begins in the North Sea west of Denmark, where it branches off from the Europipe II line, one of a web of thousands of miles of pipeline carrying Norwegian natural gas to Northern Europe across the North Sea.

With the two Nord Stream pipelines now damaged, Russia’s most efficient means for conveying gas to Europe has been disabled. Although they were each filled with limited amounts of gas, neither Nord Stream artery was transmitting the fuel at the time of the attack, because Russia had shut off 1 and Germany had never allowed 2 to begin operation.

The suspected attacks on the pipelines alarmed NATO and European countries, which have increased their patrols on the Baltic Sea. The Polish company that operates Baltic Pipe, Gaz-System, said that together with Polish authorities, the undersea stretch of the new pipeline was under surveillance “on an ongoing basis by specialized operational services.” Gaz-System declined to elaborate.

Experts point to the vulnerability of all undersea infrastructure, which beyond the energy pipelines includes thousands of miles of communication cables that in recent decades have been strung across the oceans’ floors to connect a globalized world. Keeping it safe is virtually impossible, Johannes Peters, an expert at the Center for Maritime Strategy and Security at the University of Kiel told the German reporting collective RND.

“You have to operate on the assumption that it is not possible to monitor the entire length of submarine infrastructure,” Mr. Peters said.

Many experts believe that the timing of the suspected attacks, which laid bare the vulnerability of critical infrastructure, was no coincidence. News that the leaks had reached the surface broke on Tuesday, hours before Mr. Morawiecki and his Danish counterpart ceremoniously opened Baltic Pipe. Mr. Schmitt noted that the new link played a key role in securing energy independence in a region formerly controlled by Moscow.

“The Russians have long been outraged by Baltic Pipe, because it is the first time that Central and Eastern Europe would have a direct, major pipeline route that is bringing non-Russian natural gas from the North Sea to the region,” he said.

Since the ruptures in the Nord Stream links were reported, Norwegian and French energy companies have reported suspicious aerial drone activity around their offshore installations in the North Sea.

Ylva Johansson, the European Union’s top security official, told German public television ZDF on Wednesday that the bloc had begun imposing tighter protection for critical infrastructure across member states several years ago. In the wake of the leaks, it will look into requiring member states to take further steps to ensure security, she said.

“I think this is really an alert for us that we need to act much more thoroughly to protect ourselves against these kinds of attacks,” Ms. Johansson said.

The day after the ruptures were discovered, Denmark increased its security over energy infrastructure to the second-highest alert level. Officials in Norway, where drones have been sighted flying over oil and gas infrastructure in the North Sea, in possible violation of the safety zones above installations like offshore oil platforms or pipeline pressure stations, said it would increase its military patrols.

“The armed forces will increase our visibility and presence in areas around our oil and gas installations,” said Thomas Gjesdal, the commander captain at the Norwegian Defense Operational Headquarters. “This applies to presence and patrols with forces on land, in the air, at sea, underwater and in the cyber domain.”

Sabotage against energy infrastructure has been common in recent conflicts in the Middle East, including Syria and Iraq, said Cecilie Hellestveit, an expert on international law at the Norwegian Academy of International Law.

“What is new is that this is happening in Europe,” she said. “We are not used to this type of threat, and it exposes us in ways we are unaccustomed to.”

Henrik Pryser Libell contributed reporting from Oslo.