Russian President Vladimir Putin said U.S.-led NATO was refusing to discuss easing increasing tensions. NATO disputed this.
German Foreign Minister Heiko Maas said Europe must create a new system for financial transactions that excludes the U.S. in order to help Iran.
It is "highly likely" that the U.S. will send forces on a permanent basis, the Polish defense minister said.
Analysts warn that Turkey's feud with the United States could motivate Ankara to start looking for new friends, and Russia appears happy to fill in the gap.
The Spanish Air Force fighter jet was flying alongside one Spanish and two French aircraft when it accidentally launched an air-to-air missile above Estonia.
NATO and Georgian troops are currently conducting military training exercises.
What Romanian Defense Minister Mihai Fifor called "a misunderstanding," Russian diplomat Pavel Alekseenko called "a spontaneous truth."
The president did not clarify which U.S. allies he considers to be ruled by dictators a month after Defense Secretary Mattis hailed NATO as union of "democratic nations."
He forces foreign policy and political establishments to re-evaluate positions that have been taken for granted—then says something imbecilic.
Trump must decide between chaos and leadership.
"Strengthening Russia as an independent international player does not give rest to our NATO colleagues," Russian Defense Minister Sergei Shoigu said.
"This trend clearly indicates that NATO countries are trying in every possible way to prevent Russia from emerging as a geopolitical competitor."
Greece has expelled several Russian diplomats for their alleged interference in the country's foreign policy.
Only 37 percent of Germans believe the continent needs U.S. protection.
Tensions remain high between Moscow and Washington despite Donald Trump's Helsinki summit with Russia's Vladimir Putin.
The German chancellor said she did not know the "root cause" of Trump's negative attitude toward Berlin.
Many Americans seem to be buying President Trump's anti-NATO—and often misleading—rhetoric.
"With this kind of president, with his knowledge of foreign policy, who knows what is going on? Foreign policy is not his big thing."
The Republican senator said Trump is "playing right into Putin's hand."
The Balkans could be the first test of whether President Donald Trump will side with NATO or Russia.
When Tucker Carlson asked why his son should be sent to defend Montenegro, Trump said: "I understand what you're saying. I've asked the same question. Montenegro, you know, is a tiny country with very strong people."
The CEO of Russia's Rostec state corporation said that the company developed "a coating that, like a chameleon, mimics the color of the environment."
"Sadly, it is not being reported that way – the Fake News is going Crazy!" the president tweeted.