Tens of thousands of demonstrators were descending yesterday on two southwest German towns and the French city of Strasbourg to protest a cross-border NATO summit marking the alliance's 60th anniversary.

US President Barack Obama, German Chancellor Angela Merkel and French President Nicholas Sarkozy were among 28 world leaders expected to be on hand for the two-day summit beginning today.

German authorities have estimated that some 20,000 to 25,000 protesters will take part in several planned demonstrations on the German side of the border, while France's interior minister has suggested 30,000 to 40,000 could show up in Strasbourg. The activists plan to march across the Rhine River into Strasbourg, with a follow-up protest planned for tomorrow before the meeting wraps up.