Montenegro became the 29th member of NATO on Monday and was praised by the United States for sticking to its path of joining the Western military alliance in spite of Russian pressure.

Even as Montenegrin Prime Minister Dusko Markovic was in Washington for a State Department ceremony to mark the accession, Russia warned of retaliation against Montenegro’s “hostile course” and condemned the country’s “anti-Russian hysteria.”

After the ceremony, Markovic met U.S. Vice President Mike Pence at the White House, but not President Donald Trump, officials said.

Markovic’s first encounter with Trump raised eyebrows last month, when the U.S. president pushed him aside at a NATO summit at which he demanded that allies boost defense spending to ease the burden on the United States.

Markovic told Pence that Montenegro aimed to meet the NATO target of spending 2 percent of its GDP on defense by 2024.

Russia’s Foreign Ministry said Montenegro bore “full responsibility” after joining EU sanctions against Russia in 2014.

“In the light of the hostile course chosen by the Montenegrin authorities, the Russian side reserves the right to take retaliatory measures on a reciprocal basis.

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