Top NATO and European military officials called in Berlin on Wednesday for more military spending to deal with threats to Europe and said that would help address concerns raised by U.S. President-elect Donald Trump.

During his election campaign, Trump questioned whether the United States should protect allies seen as spending too little on their defense, raising fears he could withdraw funding for NATO at a time of heightened tensions with Russia.

In Brussels on Wednesday, the European Union unveiled its biggest defense funding and research plan in more than a decade to reverse billions in cuts and demonstrate that it wants to pay for its own security.

"The best answer to Mr. Trump is to prove that he's wrong, to prove that Europe is strong enough to defend itself," French Admiral Philippe Coindreau, vice chief of defense staff, said during a panel discussion at the Berlin Security Conference.

"I think European nations should increase their defense budgets."

Trump's comments have unsettled many in Europe. But NATO said he spoke with NATO Secretary-General Jens Stoltenberg earlier this month and they agreed on the "enduring importance" of the Western alliance.

Trump has also spoken twice with British Prime Minister Theresa May and touched on the importance of NATO for European and U.S. security, Peter Watkins, director of general security policy for the British Ministry of Defense, told the conference.

President Barack Obama, NATO Secretary General Jaap de Hoop Scheffer and fellow NATO leaders step down from a photo platform April 4, 2009, following their group photo at the NATO meeting in Strasbourg, France. Official White House Photo by Pete Souza

Watkins said he was "pretty confident" that Trump would make a clear statement about his commitment to the NATO alliance.

Czech General Petr Pavel, who heads the NATO military committee, said U.S. demands for higher military spending were nothing new.

Pavel said it was more important to focus on tangible improvements in military capabilities than fixate on the 2 percent target, which he said was "too far and too big" for many NATO members to meet anytime soon.

NATO's European members cut defense spending to historic lows after the break-up of the Soviet Union a quarter of a century ago, leaving the United States to make up around three-quarters of the alliance's military expenditure.

Spending has increased in recent years after Russia's annexation of the Crimea region of Ukraine, the growing threat of Islamist attacks and large migrant flows. However, only Britain, Poland, Greece and Estonia meet a NATO goal of spending at least 2 percent of gross domestic product on defense.