Bolton is a critic of the European Union. In his book "Surrender Is Not an Option", he criticized the EU for pursuing "the endless process of diplomatic mastication" rather than satisfactorily solving problems, and he labeled the organization's diplomats as "EUroids". He has also criticized the EU for advancing what he considers liberal policies. Bolton campaigned in Ireland against further EU integration in 2008, and he criticized the Treaty of Lisbon for expanding EU powers. In 2016, Bolton praised the UK's referendum vote to leave the EU, and "Axios" reported in January 2019 that Bolton continued to advocate for a hard Brexit as National Security Advisor. In a March 2019 interview with Sky News, Bolton criticized the UK "political class" for not implementing the Brexit vote.