The first sign of change came as our convoy of food aid and medicine pulled up to the last northern town held by the Malian army. The atmosphere was tense as the heavily armed troops searched our car and baggage. Even my toothbrush was apparently suspect.

“We’re looking for weapons,’’ a soldier snapped.

“But there’s only food here,’’ one of the convoy leaders replied lightheartedly. Normally a joke like that would break the tension in Mali, but the soldier just continued his search, stony faced.

The reinforced roadblock was erected in a neighborhood on the outskirts of Mopti, 400 miles (600 kilometers) and a daylong drive from the Malian capital of Bamako. To the north lies my hometown, the fabled city of Timbuktu, now in the hands of two armed rebel groups.

Two months ago Tuareg rebels declared an independent state in the north amid a power vacuum created by the March 21 coup that ousted Mali’s longtime leader. The Malian army was forced from the north as the Tuareg fighters descended on Timbuktu.

The first group was secular and claimed to be fighting for an independent homeland for the Tuaregs, a nomadic Muslim people who live in four nations in the region. They were quickly superseded by a group of Islamist fighters known as Ansar Dine, or Defenders of Islam, whose goal is to impose Shariah law in the area they now call the Azawad nation.

The Malian soldiers were especially suspicious of me. Unlike the black African inhabitants of southern Mali — whose members dominate the army — I am light-skinned. I look Tuareg, even though I am from one of the Arab tribes that long ago settled in Timbuktu. That makes me suspect, since I look like the fighters that took over the north.

I was faced with aggressive and suspicious looks. When I tried to go out for a walk, a colleague quickly stopped me and told me I was better off staying inside until the convoy was moving again.