BRUSSELS, July 11 (Xinhua) -- The North Atlantic Treaty Organization (NATO) leaders "are committed to improving the balance of sharing the costs and responsibilities", according to a summit declaration published on Wednesday.

"Fair burden sharing underpins the Alliance's cohesion, solidarity, credibility, and ability to fulfil our Article 3 and Article 5 commitments," the summit declaration said.

NATO Secretary General Jens Stoltenberg at a news conference following the summit: "We all agree that we do not have fair burden-sharing in our Alliance today. We all agree that we need more cash in national defense budgets; More modern capabilities; And more contributions to missions and operations. The good news is that we are making progress."

According to the declaration, all Allies have started to increase the amount they spend on defense in real terms and some two-thirds of Allies have national plans in place to spend 2 percent of their Gross Domestic Product(GDP) on defense by 2024.

"We are committed to improving the balance of sharing the costs and responsibilities of Alliance membership," the declaration added.

U.S. President Donald Trump has long held criticism against U.S. allies across the Atlantic that European members of NATO are not spending enough on defense.

However, Trump at the summit told NATO leaders they should increase their defense spending to 4 percent of their country's GDP (gross domestic product), higher than NATO's goal of 2 percent, a White House official said on Wednesday.

When asked for response to that, Stoltenberg said he will focus on what they have agreed.

"We have agreed to be committed to the pledge to increase the defense spending to 2 percent, let's start with that," the secretary general said.

Despite differences and disagreement, NATO has made decisions that "we are delivering our defense pledge," he said.