Facing a skeptical crowd of fellow foreign ministers during his first visit to NATO, Rex Tillerson won applause for lunchtime remarks about the need for strength and unity in dealing with Russian President Vladimir Putin, five diplomats who were in the room told POLITICO.

The U.S. Secretary of State initially planned to skip Friday's meeting in Brussels, citing a conflict with a visit to Washington by Chinese President Xi Jinping. That caused consternation among allies, prompting NATO Secretary-General Jens Stoltenberg to reschedule so that Tillerson could attend.

Still, ministers were not sure what to expect from the former chief executive of Exxon Mobil, now working for a president who called NATO "obsolete" during his campaign.

U.S. Secretary of Defense James Mattis and Vice President Mike Pence, visiting its Brussels headquarters in February, carried Donald Trump's demand that allies increase military spending. But both were already somewhat familiar to diplomats — Mattis from his time as a NATO uniformed commander and Pence from his long service in the U.S. Congress.

Tillerson, by contrast, had never worked in public service and his reported close ties to Putin and Russia, where Exxon has invested billions of dollars in oil projects, added to NATO diplomats' wariness.

But the Secretary of State appeared to have sounded the right notes, expressing unwavering support for NATO. "The U.S. commitment to NATO is strong and this alliance remains the bedrock for transatlantic security," he said.

"The United States is committed to ensuring NATO has the capabilities to support our collective defense," he said. "We understand that a threat against one of us is a threat against all of us, and we will respond accordingly."

"The president supports NATO. The U.S. Congress supports NATO," Tillerson said.

But it was at lunch that he won applause. After one minister spoke of taking a two-tier approach with Russia, adding that "it takes two to tango," Tillerson responded: "Sure, you can dance with Russia and you might also gain something out of it. But for sure you cannot tango with [Sergey] Lavrov because he is not allowed to dance that one." The implication, diplomats said, was that only one man is in charge in Russia.

Asked how Tillerson was received, one European NATO ambassador said: "With an ovation, I mean it literally. This is not metaphorically speaking. He actually got applause."

"I'll be honest, we didn't know what we were getting into," the ambassador said, adding: "Boy, did he deliver: he was very, very clear about the United States standing by its allies. In fact, unlike Mattis, who if you remember conditioned his support for the alliance, Tillerson's support was unconditional."

"He said, 'we stand by our friends, we stand by Article 5, no ifs or buts.'"