NATO Secretary General Jens Stoltenberg pays a visit during an International exercise "Iron Wolf 2017 /Saber Strike 2017" of NATO advance force battalion group (EFP) in Stasenai, Lithuania | Petras Malukas/AFP via Getty NATO to increase non-US spending by 4.3 percent in 2017 Romania expected to be next country to meet 2 percent of GDP spending target.

NATO allies other than the United States are expected to increase defense spending by 4.3 percent in 2017, Secretary-General Jens Stoltenberg said Wednesday.

After years of decline, military expenditures started to increase in 2015, but NATO members have come under intense pressure in recent months from U.S. President Donald Trump, who has criticized European allies for not spending enough on their own defense.

In response to Trump's pressure, allies who are not yet meeting a previously-agreed-upon target of 2 percent of annual GDP being spent on defense have agreed to step up efforts to move toward that goal. At a meeting in Wales in 2014 they agreed "to move towards the 2 percent guideline within a decade”

At a news conference on Wednesday ahead of a meeting of NATO defense ministers, Stoltenberg noted that spending moved onto an upward trajectory in 2016, and "in 2017 we foresee an even greater annual real increase of 4.3 percent.”

“This means, over the last three years, European allies and Canada spent almost $46 billion more on defense,” Stoltenberg, a former prime minister of Norway, said.

This week's defense ministerial meeting is the first gathering of senior NATO officials since a leaders' meeting last month where Trump publicly berated his colleagues during a ceremony to open the alliance's new headquarters.

Trump disappointed European partners who hoped he would use the occasion to explicitly reaffirm America’s commitment to NATO's collective defense principle, which is enshrined in Article 5 of the NATO treaty.

Currently, 25 out of 29 NATO allies plan to raise defense spending this year, Stoltenberg said, a move that would add Romania to the list of five allies (U.S, U.K, Greece, Estonia and Poland) currently meeting the 2 percent target. Next year, Lithuania and Latvia are also expected to cross the threshold.