Cohen was for many years a critic of Tony Blair's foreign policy. He began modifying his views after 2001, advocating the 2003 invasion of Iraq, and becoming a critic of the Stop the War Coalition. In 2006, he was a leading signatory to the Euston Manifesto, which proposed what it termed "a new political alignment", in which the left would take a stronger stance in favour of military intervention and against what the signatories deemed to be anti-American attitudes. Cohen supported the NATO-led intervention in Libya to oust former Libyan leader Muammar Gaddafi in 2011. In 2012, he called for Western military intervention in the Syrian Civil War.