A U.S. Senate staffer says North Korea's military may block diplomatic efforts to end that country's nuclear program.

Senate staffer Keith Luse on Friday submitted to the Senate Foreign Relations Committee a report on his visit to Pyongyang last month.

The aide to Senator Richard Lugar said in the report that North Korean leader Kim Jong-il’s efforts to balance competing interests within the North may be a "stretch too far" for his country's military hard-liners.

Luse added that declaring and discarding nuclear programs will be difficult for military hard-liners who view nuclear weapons as the ultimate deterrent.

Meanwhile, Siegfried Hecker, who accompanied Luse on last month's Pyongyang visit, commented on the trip in a separate report. He said the North told him it will abide by an agreement reached last October not to transfer nuclear materials, technology or know-how.