KLAIPEDA, Lithuania — The vast ship that eased into this misty seaport early on Monday was hailed by American and European officials as the strongest signal that the stranglehold Russia has on the Baltics and their energy needs can be broken.

The vessel, the Independence, is a floating factory for converting liquefied natural gas into the burnable variety. It represents a direct challenge to the Russian way of doing business as many other countries in the European Union have dithered over how to deal with President Vladimir V. Putin and his attempts to reassert Russian influence over parts of the former Soviet empire like Ukraine.

“We are now an energy-secure state,” Dalia Grybauskaite, the Lithuanian president, said at a ceremony that featured martial touches like a naval brass band, red flares and a cannon salute. “Nobody else from now on will be able to dictate to us the price of gas, or to buy our political will, or to bribe our politicians.”

“If we don’t like it, we can drop it fully and totally,” Ms. Grybauskaite said, referring to a possible severing of relations with Gazprom, the government-controlled Russian gas exporter, which supplies all of Lithuania’s gas.