WASHINGTON -- Analysts are warning that an alleged coup attempt last year by Russian agents that Montenegro said was foiled will likely be repeated, and Washington needs to do more to shore up "Europe's soft underbelly."

The analysts spoke at July 13 hearing of the U.S. Senate Armed Services Committee that focused on the overall situation in the Balkans.

The alleged coup attempt "was not the first, nor likely will it be the last, of Russia's attempts to undermine the sovereign right of a nation to freely choose its political associations," said Lisa Samp, who worked on Russian and European affairs at the White House and Defense Department.

Damon Wilson, executive vice president for the Atlantic Council, a Washington think tank, said Russia was seeking to expand its influence, and undermine Western-leaning governments using "a nexus of corruption, organized crime, and underdevelopment."

"Prosperity is the antidote, as it increases the resilience of nations, particularly in Europe's east and southeast," he said.

Nebojsa Kaludjerovic, Montenegro's ambassador to the United States, told senators that the trial of several alleged coup plotters was ongoing, and the chief prosecutor had called the evidence "ironclad."

He said two Russians believed to be military intelligence agents were involved, as well as several Montenegrin politicians, and a former Russian deputy military attache had been kicked out.

"If the plans had succeeded, there would have been chaos, serious violence, and extremely dangerous instability," he told the panel.

Montenegro recently joined NATO, which Moscow strenuously opposed.