A delegation of U.S. lawmakers met with military officials in Mali's capital on Monday, and urged caution as the French-led military intervention to wrest back control of the country's north from the al-Qaida fighters entered its fifth week.

French President Francois Hollande unilaterally launched the intervention last month after the extremist groups began a push south. They later reached out to allies for logistical help. The United States is providing C-17 transport planes and in-air refueling, as well as help with intelligence gathering, but has ruled out sending troops.

The four lawmakers are led by Sen. Chris Coons, a Delaware Democrat who chairs the Senate Foreign Relations subcommittee that oversees Africa issues. After meeting with French military officials as well as their Malian counterparts, Coons told The Associated Press by telephone: "My initial impression is that the French are very confident that their military intervention has been swift, decisive and effective in driving the jihadists completely out of towns in the north."

But he added: "My concern ... is that there are longstanding internal tensions in Mali that reflect development challenges, and political fractures and ethnic tension that may be dramatically worsened by how the French and their allies ... and the Malians conduct themselves in the field in the next few weeks."

Among the worrying signs are the recent back-to-back terrorist attacks in the newly-freed city of Gao in the north. Columns of French forces have had to double back to Gao to reinforce the town, even as a different unit of French troops continues to push northward. The suicide attacks, he said "suggest a level of jihadist militancy that doesn't reflect the confidence that I heard from the French — that the jihadists are not from here, are not supported here, and have been driven away."

Over the weekend, French forces secured the small town of Bourem, located between Gao and Kidal. French and Chadian forces were also patrolling the city of Kidal, though it remains unclear if the northern administrative capital is secure. The roads connecting the towns remain unsafe, with repeated sightings of jihadist convoys as well as several fatal incidents involving landmines planted by the extremists.

Mali, a landlocked nation of nearly 15.8 million, has long been among the poorest in the world, but until last year, it was viewed as relatively stable despite the infiltration of its remote deserts by al-Qaida in the Islamic Maghreb. The extremists took advantage of a March 2012 coup in the capital in order to push into the main cities in the north, including Timbuktu, where residents are just now starting to fully regain the freedoms they lost during 10 months of Islamic rule.

The four person delegation also includes Sen. Johnny Isakson, R-GA, Rep. Karen Bass, D-CA, a ranking member of the House Foreign Affairs Subcommittee on Africa, and Rep. Terri Sewell, D-AL.