BERLIN — German Foreign Minister Johann Wadephul’s unexpected support for a dramatic increase in defense spending to 5 percent of GDP is dividing the country’s ruling coalition.

The target represents a steep increase from the 2 percent of GDP that Germany now spends and is in line with demands from U.S. President Donald Trump.

NATO’s current target, set in 2014, is for members to spend at least 2 percent of GDP on defense, but that is likely to be upped at a June summit in The Hague.

Germany’s center-left Social Democratic Party (SPD), which governs alongside Chancellor Friedrich Merz’s conservative Christian Democrats (CDU/CSU), warned against unilateral moves and urged coordination within the coalition and with NATO allies ahead of the summit.

“We acknowledge our special responsibility in foreign, defense and development policy. Europe will have to do much more to ensure its own security in the future,” SPD lawmaker Adis Ahmetovic told POLITICO. “But I urge everyone not to go it alone now. The budget will have to be negotiated jointly within the alliance.”

Ahmetovic also reminded Wadephul of the coalition agreement between the two parties, which he said “clearly lays out the framework for foreign policy,” adding that the federal budget “must be agreed upon within the coalition.”

But other Christian Democrats backed Wadephul.

“The significant increase in defense spending is a consistent implementation of the chancellor’s stated goal to build the largest conventional army in Europe, as well as of the commitments laid out in the coalition agreement,” said Thomas Erndl, an MP who is the CDU/CSU parliamentary spokesperson on defense policy.

The criticism from the SPD reflects the party’s growing unease with the scope and speed of Germany’s rearmament.

One SPD MP, who spoke to POLITICO on condition of being granted anonymity, said Wadephul’s announcement was “not wise,” arguing that the proposed 5 percent target is “not conceptually underpinned” and risks undermining the fragile consensus for higher defense spending.

“There is broad agreement — across the SPD, CDU/CSU and the Greens — that Germany’s share of GDP spent on defense must rise significantly,” the MP said. “But that unity should not be jeopardized by rash announcements.”

According to the same MP, the government had previously agreed to wait until the NATO summit to name a spending target. “Wadephul’s move was not coordinated within the government,” the lawmaker added.

But conservatives backed Wadephul, a Christian Democrat, who made the remarks Thursday morning at a meeting of NATO foreign ministers in Antalya, Turkey. “Germany is ready to follow this target,” the minister said, adding that the country is “prepared to take a leading role in securing Europe’s future.”

The CDU/CSU’s Erndl stressed that while the final figure will be determined at the June summit, Wadephul’s comments “reflect the consensus within both NATO and the coalition.”

NATO Secretary-General Mark Rutte has previously said he wants the alliance to spend 3.5 percent of GDP on defense, with another 1.5 percent on related security goals like military mobility.

Erndl said “it makes perfect sense” to include infrastructure spending alongside traditional military items in a higher defense budget.

Merz, in agreement with the SPD and other parties, has already agreed to exempt defense spending from Germany’s constitutional debt brake and launched a €500 billion modernization fund.

The chancellor said last week that each additional percentage point of defense spending would mean an annual expenditure of €45 billion — so Wadephul’s pledge is worth about €135 billion.