A Cato press release details Klaus's close connections to Cato over the years:
Klaus has been a regular guest at the Cato Institute over the years, speaking for the first time in 1992 as finance minister of Czechoslovakia. Cato has published multiple articles and lectures by Klaus on topics including the environment, the fall of communism, and the Eurozone.
“I consider the Cato Institute one of the most prominent public policy research organizations in the United States which has been consistently advocating the classical liberal principles,” Klaus said in a letter to Cato Founder and President Emeritus Edward H. Crane. “I am truly honored to join Cato.”
Klaus will headline an event at Cato on March 11, The European Crisis Continues: No Solution on the Horizon.The press release also notes that Klaus has also started his own think tank in the Czech Republic, the Václav Klaus Institute, in Prague.
Here is a December 2012 interview with Klaus in which he discusses his new think tank, including the fact that he is "not very happy" that the institute will bear his name.
Klaus will not be the first former foreign president to join a US think tank. Here is a previous Think Tank Watch Post on foreign influence in US think tanks. It notes, for example, that the former heads of state of Mexico, Colombia, Singapore, and Finland are closely affiliated with US think tanks.
The Cato Institute was just ranked as the 19th best think tank in the world by the University of Pennsylvania think tank rankings. That same ranking said it is the 10th best think tank in the US.
Another ranking by the Center for Global Development (CGD) lists Cato as the #1 US think tank.