WASHINGTON, May 21 (Xinhua) -- A Pentagon watchdog said Monday that U.S. troops has made "minimal progress" in Afghanistan during the first quarter of 2018 as challenges facing U.S. and Afghan forces mount.

In a quarterly report to Congress, the Lead Inspector General for Overseas Contingency Operations said the population living under secured environment has shown little positive change since the fourth quarter last year, demonstrating the stalling military effort of U.S. troops in the country.

The report tallied 65 percent of the Afghan population as living in areas controlled by the Afghan government, compared with 64 percent last year. U.S. and Afghan officials have stated that the goal was to raise the number to 80 percent at the end of 2019 to squeeze out the Taliban.

The report, undersigned by the Inspector Generals of the Department of Defense, the State Department and the U.S. Agency for International Aid, identified dwindling forces, rampant attacks and corruption as major challenges facing Afghan government forces.

As of Jan. 31 this year, the Afghanistan National Defence and Security Force (ANDSF) has 313,728 personnel, compared with 331,708 from a year ago. The drop "renews concerns about the recruiting, retention and casualty rates of the ANDSF and the overall effectiveness of the ANDSF," the report said.

It also noted that despite efforts to bolster security, militants carried out at least 10 attacks in Kabul during this quarter. Corruption also continues to undermine the effectiveness of Afghan forces as the country slipped four spots on a global corruption index last year.

Pentagon spokesman Robert Manning on Monday downplayed the grim picture in Afghanistan, saying that "Chaos and progress can coexist and that's exactly what we feel is happening in Afghanistan," adding that "We feel like progress is being made."