Russian President Vladimir Putin has dismissed as “sheer nonsense” allegations that Ukrainians could be behind the explosions that crippled the Nord Stream gas pipelines, suggesting the United States may have been responsible.

The Russian leader insisted on Tuesday the US had a motive to carry out the attack in the Baltic Sea last year, saying it wanted to halt supplies of cheap Russian natural gas to Europe and provide the continent with more expensive liquefied natural gas.

“Who is interested? Theoretically, the United States is interested in stopping the supply of Russian energy to the European market and supplying volumes of its own,” Putin told an interviewer.

“Such an explosion, so powerful and at such depth, could only be conducted by experts backed by the entire potential of a state that has relevant technologies,” he added.

Putin spoke after The New York Times, The Washington Post, and German media published stories last week citing unidentified American and other officials as saying there was evidence Ukraine – or at least “pro-Ukraine groups” – may have been responsible for the blasts. The Ukrainian government denied involvement.

Germany’s Die Zeit newspaper and German public broadcasters ARD and SWR reported that investigators believe five men and a woman used a yacht hired by a Ukrainian-owned company in Poland to carry out the attack. German federal prosecutors confirmed a boat was searched in January but have not confirmed the reported findings.

The Kremlin last week described the claims about Ukrainian involvement in the explosions as part of a cover-up by the West.

Putin said the blasts were carried out on a “state level” and dismissed as “complete nonsense” suggestions an autonomous pro-Ukraine group was responsible.

Germany ‘occupied’

Germany’s response to the explosions showed the country remained “occupied” and unable to act independently, decades after its surrender at the end of World War II, Putin said.

“Germany was never a fully sovereign state,” Russian news agencies quoted Russia’s leader as telling state-owned Rossiya-1 TV channel.

“The Soviet Union at one point withdrew its forces and ended what amounted to an occupation of the country. But that, as is well known, was not the case with the Americans. They continue to occupy Germany.”

The Nord Stream pipelines were intended to bring Russian gas to Germany, though since Moscow’s invasion of Ukraine a year ago Berlin has taken steps to reduce its reliance on Russian hydrocarbons.

Leaders in Berlin have been careful about apportioning blame for the explosions with Defence Minister Boris Pistorius saying last week the blasts could have been a “false-flag operation to blame Ukraine”.

Putin also poured scorn on European leaders for keeping quiet about the incident, saying their attitude reflected what he described as Europe’s subservient position in relations with the US.

“The Europeans have lost a gene of independence, sovereignty and national interest,” Putin said with a smirk. “The more they [Americans] hit them on their noses or the top of their heads, the lower they bend and the broader they smile.”

Massive methane gas release

September’s explosions that hit the Nord Stream 1 and Nord Stream 2 pipelines rendered them inoperable and caused significant leaks of methane gas.

The leaks in the Baltic Sea led to what is likely the biggest single release of climate-damaging methane ever recorded, the United Nations Environment Programme said.

Western countries, including Germany, have said they believe the blasts were a deliberate act, but declined to say who they think was responsible.

US officials initially suggested Russia may have been to blame. Russia blamed the US and Britain. Investigations by European nations, including Denmark, through whose waters the pipeline travels, and Germany, have yet to yield conclusive results.

Putin voiced regret that Russia has been denied access to the materials of the probe. He added the Russian Gazprom natural gas giant has sent a vessel to check the seabed near the explosion and spotted what appeared to be an antenna near a junction between the pipes about 30km (16 nautical miles) from the explosion site.

Putin alleged the antenna could have been put on the seabed to trigger another explosive device that did not detonate for a reason that remains unclear. He added Russia expects Danish authorities to form a joint team to thoroughly check the area.

In a blog post last month, Pulitzer Prize-winning investigative journalist Seymour Hersh quoted an unnamed source with “direct knowledge of operational planning” as saying the operation to blow up the pipelines was carried out by the US military and CIA – with direct approval given by US President Joe Biden.

The White House dismissed Hersh’s report as “utterly false and complete fiction”.