WASHINGTON — President Biden said Monday that he would name Qatar as a “major non-NATO ally” of the United States, a designation that will clear the way for greater security cooperation and investment in the Gulf nation at a time when Mr. Biden is seeking help boosting natural gas supplies in Europe.

The president is eager to reassure European nations that they will not suffer natural gas shortages if a war between Ukraine and Russia breaks out in the weeks ahead. Russia is one of the largest suppliers of natural gas to Germany and other countries in western Europe.

Mr. Biden’s comments on Monday came ahead of a meeting at the White House with Tamim bin Hamad al-Thani, the emir of Qatar. Speaking to reporters, the president praised the relationship between the two countries over the past half-century on issues like Afghanistan, the dispute between Israel and the Palestinians, and the fight against the Islamic State.

“I am notifying Congress that I will designate Qatar as a major non-NATO ally to reflect the importance of our relationship,” Mr. Biden said. “I think it’s long overdue.”

Only 18 other countries have been granted that status by American presidents. They include Australia, Egypt, Israel, Japan, South Korea, Jordan, New Zealand, Thailand, Kuwait, Morocco, Pakistan, Bahrain, Philippines, Argentina, Taiwan, Afghanistan and Tunisia. Former President Donald Trump conferred the status on Brazil in 2019.

Conferring the status of “major non-NATO ally” on a country does not guarantee that the United States will come to the defense of that country in the event of an attack. That guarantee — laid out in Article 5 of the North Atlantic Treaty Organization’s founding treaty — is limited to full members of the alliance.

But the designation will give Qatar more diplomatic prestige and access to technology, security systems and training by U.S. defense forces that has not been previously available to it. The move is often used to prod countries toward closer ties with the United States and other Western nations.

In the case of Qatar, Mr. Biden is hoping to deepen economic and security ties. In his remarks on Monday, the president applauded an announcement by the C.E.O. of Qatar Airways of a $34 billion deal to purchase planes from Boeing. Mr. Biden said the deal would support tens of thousands of jobs in the United States.

But the looming conflict between Russia and Ukraine is the more immediate concern for Mr. Biden, who is seeking to maintain unity with America’s European allies behind threats of sanctions on Russia if President Vladimir Putin decides to invade.

Concerns about the possibility that Russia might restrict the flow of natural gas to Europe could undermine that unity, and White House officials have said they are working with other nations around the world to provide reassurances to European leaders if that should come to pass.