When President Trump met with Jean-Claude Juncker, the president of the European Commission, at the White House, the two said they were entering a new phase in their relationship. Crucial to that will be natural gas.

Demand for natural gas — a cleaner-burning fossil fuel than coal or oil — is rising worldwide, and the United States is a growing supplier of liquefied natural gas, or L.N.G. The European Union, meanwhile, wants to diversify its energy supply, which remains somewhat dependent on Russia, with which it has a difficult relationship.

Mr. Trump said on Wednesday that the 28-nation European Union would be “a massive buyer of L.N.G.,” before adding, “We have plenty of it.”

Any such shift won’t happen overnight, though.

Europe needs more gas

In simple terms: Europe’s consumption of natural gas is increasing, and its domestic production is falling. Its imports have risen rapidly in recent years, and will most likely increase further in the future.