US in Afghanistan at US-Korea troop level and duration is now the good scenario

The United States has maintained at least 28,000 American soldiers, sailors, airmen and Marines in South Korea since the Korean War started in 1950. The US will have had a Korean war and postwar presence in Korea for 67 years.

President Donald Trump announced a new strategy in Afghanistan Monday night, saying that the U.S. will expand authority for American armed forces to target the terrorist and criminal networks that sow violence and chaos throughout Afghanistan. The troop levels in Afghanistan would be dependent upon conditions within Afghanistan.

The average number of U.S. troops serving in Afghanistan is about 11,000 to 12,000 which is higher than the official 8,400 troops on the ground. There are also about 25,000 contractors. About 3 percent of these contractors were armed private security contractors.

The combined contractor and troop levels in Afghanistan are at a combined level 37,000 and the new plan will increase it to 40,000 to 60,000 depending upon conditions. There are also US troops in Syria and Iraq.

The U.S. officially launched war in Afghanistan on 7 October 2001. This year in October it will have been 17 years of US-Afghanistan war. It is very likely that the US will not end the war within the term of this presidency. This will mean the US Afghanistan war (or even with any declared victories – postwar) will last at least 20 years.

Pakistan has nuclear weapons and a large extremist population which is connected to Afghanistan.
Iran seeks nuclear weapons and has a long history with terrorism.

The US troop level in Afghanistan will be similar to US-Korea troop level and duration. This will be 30,000 to 60,000 troops and contractors for another fifty years. This is actually the better scenario where the US does not gets involved in a wider conflict involving Iran and Pakistan. The bad scenario see troop and contractor levels going to 200,000+ with a wider conflict.