Swedish and Danish authorities have been investigating four holes in the Nord Stream 1 and 2 pipelines which link Russia and Germany via the Baltic Sea.Both pipelines have been flashpoints in an escalating energy war between European capitals and Moscow that has pummeled major Western economies, sent gas prices soaring and sparked a hunt for alternative energy supplies since Russia invaded Ukraine in February.Western nations have previously said that the leaks, which were first discovered on September 26, were likely the result of sabotage.Denmark last month said a preliminary investigation had shown they were caused by powerful explosions.The US Navy’s processing of the sonar signatures – the term for the unique underwater sounds – provided by Sweden and Denmark could boost the investigations by providing a more detailed picture of what was in the area when the incidents occurred and what caused them, sources familiar with the matter said."