"Although there has been some decline in infiltration, infiltration continues at very significant levels," he said.
US forces have faced a challenging year in the east after a spike in infiltration across the border from Pakistan.
For example, in November, there was actually a decrease in infiltration from North Waziristan, although the reason is unclear.
But he added that North Korea had an estimated 60,000 special forces, skilled in infiltration and asymmetric warfare, capable of causing havoc behind the lines.
Since General Musharraf said in a speech on May 27 that no infiltration was taking place, Indian officials have noted a declining trend in infiltration.
Indian government officials point to statistics showing a decline in infiltration from Pakistan as proof that their tough methods have worked.
After announcing the restoration of overflights, Nirupama Rao, spokeswoman for India's ministry of external affairs, said: "There has been some fall in infiltration.
Nor did India publicly announce that it has picked the man who will serve as high commissioner to Pakistan if downward trends in infiltration continue, though two senior officials confirmed it.
India's foreign minister, Yashwant Sinha, said the assurance combined with a "certain situation on the ground" -- a reduction in infiltration into Indian-controlled Kashmir and militant activity there -- gave India the confidence to proceed.
Thus, rapid decreases in infiltration rates during a rain are more likely to occur in clay-rich soils than in sandy soils.
Fok (1987) summarized developments in infiltration and its application.
