And why not? It's not as though his public statements cost him anything.
The so-called "fighting season" is over and an Afghan leader's fancy can turn to antagonizing his American patrons for amusement over the cold winter months.
Sure, NATO soldiers, the bulk of them Americans, will be fighting and dying to protect his government in Kabul even as winter embraces Afghanistan, but President Hamid Karzai will probably get even more latitude than normal for airing his views. This is among his favorite times of year to lash out at the Western powers who have given so much so that he can lead Afghanistan. Last October, he said Afghanistan would back Pakistan if the US ever ended up going to war with Afghanistan's neighbor. In April 2010, he sought to blame the UN and the EU for Afghanistan electoral fraud.
This time, Mr. Karzai is unhappy about the International Crisis Group, probably the world's leading think tank when it comes to unbiased, factual reporting on conflict (full disclosure; I briefly worked on contract for ICG 12 years ago helping to write a report on religious wars in eastern Indonesia). The Brussels-based research organization receives much of its funding from the European Union and the US, but has established a reputation for independent analysis in its 17 years of work.