from latter in the article
In a raid in Kunduz City in the north about six months ago, 13 people were arrested in a joint operation by American forces and the Afghan intelligence agency, the National Directorate of Security, according to Safiullah Amiry, the deputy provincial council chief there. Two of the main targets of the raid had already fled one to Tajikistan and one to Russia, Mr. Amiry said but it was in the Kabul home of one of them where security forces found a half-million dollars. He said the Afghan intelligence agency had told him the raids were related to Russian money being dispersed to militants.
This isn't some analytical conclusion based on analysts making conclusions based on intercepts, they went to the house and recovered the money and the people in the house told Afghan security what it was for.
The people they were chasing fled, some going to Russia.
This is like saying that the Watergate burglars who were arrested in the offices of the Democratic National Offices should not be pursued because it is a low valued source.
We didn't just have a very high valued source, we had the perpetrators and the cash.
The money was sent by bank transfer to Afghan criminal entities who then used "informal money exchanges" to pass the money to Taliban.
Typically they pass the money to relatives of the Taliban in Kabul who then let the terrorists know that payment has been received.