https://www.reuters.com/article/us-ecb-policy-libra/europe-should-ignore-treacherous-promises-of-facebooks-libra-currency-ecbs-mersch-idUSKCN1VN0H0 >Facebook's proposed Libra currency could undermine the European Central Bank's ability to set monetary policy and Europe should ignore its siren call of "treacherous promises" ECB board member Yves Mersch said on Monday.