The war of words between the Netherlands and Turkey is not the kind of fighting Secretary-General Jens Stoltenberg wants allies to be doing.

Releasing his annual report reviewing the state of the alliance in 2016, Stoltenberg said NATO had enough on its plate with fighting "Islamic State," deterring further Russian aggression and battling cyberattacks that increased 60 percent from the previous year. He encouraged The Hague and Ankara to just calm down.

"I really believe that we should be focused on the threats and challenges we see from outside the alliance and everything that unites us instead of focusing on issues that divide us," Stoltenberg said sternly.

And while he initially underplayed the dispute as a "bilateral issue" between the Netherlands and Turkey, Stoltenberg also acknowledged he'd put in calls to both governments over the weekend as the situation increasingly resembled a tinderbox. The government of Turkish President Recep Tayyip Erdogan, possessing NATO's second largest military, accused the Dutch government of being "Nazi remnants" and"fascists" after Dutch Prime Minister Mark Rutte blocked two Turkish ministers from leading a Rotterdam campaign rally in favor of giving Erdogan more power in an April 16 referendum.

"Robust debate is part of our democracies, but at the same time, mutual respect is important," Stoltenberg said. "Calm and de-escalation is important now to defuse tensions."

Despite an incursion by demonstrators into the Dutch diplomatic compound in Istanbul Sunday in which they took down the Dutch flag and put up a Turkish one, Stoltenberg said he wasn't worried about the physical safety of allied personnel stationed in Turkey or NATO facilities there. "All I can say is that I urge all allies to act in a measured and calm way to reduce tensions," he added.

EU defends member states' reactions to Turkish campaign efforts

Across town, the European Union was issuing a similar, if less even-handed, appeal. In a joint statement, EU foreign policy chief Federica Mogherini and Enlargement Commissioner Johannes Hahn said EU governments had the right to preventTurkish officials from campaigning on their territory, as German cities have done, urging Ankara to "refrain from excessive statements and actions that risk further exacerbating the situation."

But Carnegie Europe scholar Marc Pierini, who was the European Union's ambassador and head of delegation in Ankara from 2006 to 2011, says he doubts Brussels' calls for de-escalation will be heeded.

Carnegie Europe scholar Marc Pierini was the EU ambassador to Turkey for five years. He doesn't expect Erdogan to give up his chance to gain Turkish expat votes in Europe by employing "antagonistic populism".

"It's a very rough patch, and it's even more worrying that there is little hope to get things calmed down in a very short time," Pierini told DW. "This will plunge the personal relationships between the Turkish president and his European counterparts into ice-cold water for quite a bit of time."

Pierini expects that populists on both sides are likely to gain thousands of votes from the respective demonstrations of anti-Islam and anti-Europe sentiment, so neither has an incentive to stop feeding the frenzy. He explained that while they were antagonistic populist movements, they benefited each other.

Pierini said it was no coincidence that Erdogan was dispatching his ministers to the Netherlands, France and Germany, deep in their own bitter election campaigns and where millions of expatriate votes are at stake in Turkey's April 16 referendum. Erdogan and his regime "know that by bringing such a fierce narrative, they are going to trigger adverse narrative from the populist parties there and that will feed the national debate in Turkey," he said, noting the irony of the Turkish leader using the tradition of free speech in Europe to campaign to consolidate his power at home into an even more repressive regime than he currently runs.

While the tension has not spread across all of Europe yet - the Danish government asked the Turkish prime minister to postpone a visit in solidarity with the Dutch, but not to cancel it - that could change depending on Ankara's actions. If Erdogan tries to stage rallies for himself in other EU countries, or if he fulfills threats to retaliate against the Dutch in wide-ranging ways, it will be clear he wants a fight with the entire EU. Brussels will have to weigh Erdogan's warming relationship with Russian President Vladimir Putin when it considers its own response.

Pierini is pessimistic about how rapprochement might evolve. "It's very easy to dig this hole," he said, "but it's very difficult to climb out." He said the only hope was that while personal relationships went south, institutional relationships remained stable.