Failure to reach an agreement on Greece's bailout could result in rapid economic deterioration, geopolitical disruption and increased risk of terrorism in Europe and the United States, experts told CNBC on Wednesday.
Greece went into arrears Tuesday after failing to make a 1.6 billion-euro debt payment to the International Monetary Fund. The country has limited the amount of money Greeks can withdraw from banks as the country's financial institutions run dangerously low on cash.
The capital controls are just the tip of the iceberg, said Anastasios Economou, founder of international investment holding company iGroup. Greece's businesses are already finding it difficult to purchase products and have started turning down credit cards, and shortages of critical goods may come next, he said.
"At the end of the day you're looking at machinery, pharmaceuticals, fuel. All these are imported. Sooner or later, that guy that needs to make a payment abroad and can't will start facing shortages," he told "Squawk Box." "That's where I think you get the second wave, which is going to be even worse for the economy."
The Greek government on Wednesday said in a letter it was willing to make concessions in order to unlock badly needed aid that would allow it to avoid defaulting on a payment to the European Central Bank this month. However, Prime Minister Alexis Tsipras said the country would go through with an announced referendum on creditors' proposals, which would impose further austerity measures on Greece.
The referendum is largely irrelevant, said Economou, who also serves as the Young Presidents' Association's regional president for southern Europe. No matter the outcome, the Greek economy will continue to deteriorate as the country either fine tunes an agreement with Europe or plots its exit from the euro zone, he explained.
"The idea there is ... the "no" should get us more negotiating power," he said. "Europe doesn't see it that way, and I think it's very important that people understand that and make that distinction."
Putting aside the play-by-play and focusing on the fundamentals, Greece faces a dire situation in the medium-term, however Greeks vote on Sunday, said Daniel Speckhard, former U.S. ambassador to Greece and Belarus.
Even if Greeks vote in favor of the creditors' proposal, few think the government will be able to maintain a program backed by the International Monetary Fund that would consistently grow Greece's primary surplus in the middle of an economic contraction, he said.
Still, the lion's share of blame for the present situation falls squarely with Greece, he told CNBC's "Squawk on the Street," "It was a monumental miscalculation to call for this referendum before they knew where they were headed and how it was going to turn out."
At the same time, European creditors made a mess by pushing forward a program that required austerity measures that were unsustainable, he said. "After five years, you can't keep the political momentum for that, so I think there was a miscalculation on that side, as well."
Importantly, Speckhard noted, Greece is a member of the European Union and NATO, both consensus-based organizations. "If things fall apart and they are angry and upset, they can play a real spoiler in both those institutions" on issues including Russian and Iranian sanctions, he said.
A destabilized Greece also raises the risk that terrorism will spread due to its geographic location.
"It's basically the back door for people from the Middle East and refugees from around the world into the European Union, and if they don't monitor that, you could have some nefarious characters working their way into a free European travel zone to the rest of Europe and eventually to the United States," he said.
If Greece falls apart, it would not be hard for someone to obtain a Greek passport even if he or she is not a true Greek, he said.