From 1999:

Milton Friedman argued that the ECB's monetary policy in the euro zone was too tight and that it should do quantitative easing to stimulate the economy, similar to his advice for the Bank of Japan in the late 1990s[1]. Friedman believed the euro was a mistake that would exacerbate economic and political tensions in Europe[2][4].

In 1997, Friedman recommended that the Bank of Japan increase the money supply by buying government bonds to boost economic growth and inflation[1]. However, Japan's current inflation strategy of targeting a 2% rate is exactly what Friedman warned against, as it requires the central bank to actively manage inflation expectations[3].

Friedman believed Japan's economic recovery from the 1970s oil crisis was due to government spending supplementing steady monetary growth, supporting Keynesian theory[5]. He also noted Japan's unique labor dynamics and government-business cooperation helped restrain inflation[5]. However, Friedman cautioned against overemphasizing the benefits of government intervention, arguing Japan's prosperity stemmed from its free market policies[5].

Sources [1] Friedman's Japanese lessons for the ECB - The Market Monetarist https://marketmonetarist.com/2012/08/15/friedmans-japanese-lessons-for-the-ecb/ [2] [PDF] Why the Euro is a Big Mistake - Collected Works of Milton Friedman https://miltonfriedman.hoover.org/internal/media/dispatcher/214327/full [3] Japan's Inflation Strategy Is Exactly What Milton Friedman Warned ... http://www.wsj.com/articles/japans-inflation-strategy-is-exactly-what-milton-friedman-warned-against-1478812240 [4] They Told You So: Economists Were Right to Doubt the Euro https://www.nytimes.com/2015/07/19/business/history-echoes-through-greek-debt-crisis.html [5] [PDF] Japan — Free To Choose - Collected Works of Milton Friedman https://miltonfriedman.hoover.org/internal/media/dispatcher/271046/full