Appointed captain in Vermaelen's absence, Kompany will now lead the country on a permanent basis.
"I still thought I was going to be captain," Vermaelen told Sky Sports News.
"I had not expected that [to lose the captaincy], I found it a great honour to be captain of my country so of course I am disappointed that I will no longer carry the armband.
"Even though I was absent for a long time, I thought I would be [manager Georges Leekens'] captain.
"I have not talked with Vincent [Kompany] about it, but I don't need to."
Although Belgium suffered early EURO 2012 heartbreak by not reaching the finals, the Arsenal vice captain is optimistic for future tournament success.
“We are clearly developing which is positive for everyone to see," he said. "Players like Steven Defour and Axel Wistel have now joined bigger clubs and have already got better."
Defour and Witsel both left Belgian Pro League side Standard Liege to move to Portugal this summer, with Porto and Benfica respectively.
Belgian national team manager George Leekens declined to discuss the captaincy issue, but shared Vermaelen's optimism regarding the future of the side: "I am very happy he is back, he remains the standard bearer of the national side and is one of seven or eight players that will lead the Red Devils ahead of the 2014 World Cup.”