If you broke it, you own it.
Afghans we bring in due to their having aided the U.S. will be the fourth time this has happened in large numbers since the 1960s. Based on the figures in prior waves, and the size of the countries of origin, some 100,000 Afghanis (workers and their families) might be expected. The Biden administration could easily have foreseen this well before it announced in mid-April that it will close down its military presence in the country in September.
I summarize here the flow of Hmong, Vietnamese, and Vietnamese persons and their families admitted to the U.S. on the basis of their helping the U.S. during the Vietnam and Iraq Wars. The populations of these nationalities/ethnicities in the U.S. now comprise families and descendants of those who helped the U.S. during the wars; subsequent political refugees; and persons who who arrived not as refugees.
Most Hmong Americans consist of those that fled to the United States as refugees in the late 1970s due to their cooperation with the CIA in Laos during the Vietnam War, and their descendants. Initially, only 1,000 Hmong people were evacuated to the US. In May 1976, another 11,000 Hmong were allowed to enter the United States. By 1978 some 30,000 Hmong had immigrated to the US. The Refugee Act of 1980 led to a second wave of Hmong refugees.
Current Hmong-American population: about 300,000, including second and third generation. Hardly any had arrived before the Vietnam War. See here.
The week before Saigon fell, 15,000 people left on scheduled flights followed by an additional 80,000 also evacuated by air. The last group was carried on U.S. Navy ships. They were largely the educated elite. One estimate of the number of persons who worked for the U.S. and their families who were brought to the U.S. immediately after the war is 138,000.
A second wave of Vietnamese refugees, not associated with persons who helped the U.S. arrived from 1978 to the mid-1980s. Many South Vietnamese fled on fishing boats. From 1978 to 1982, 280,500 Vietnamese refugees were admitted. Between 1981 and 2000, the country accepted 531,310 Vietnamese political refugees.
Current Vietnamese-American population: 1.3 million, including second and third generation. Few had arrived before the Vietnam War. See here, here and here.
As of 2019, An estimated 110,000 Iraqis were waiting to be approved as refugees based on their wartime assistance. Prior to then, the United States admitted annually 500 – 5,000 a year.
Current Iraqi-American population: about 150.000, including second generation. Many had arrived before the Iraq War. See here and here
Between the mid 1990s and the Trump Administration roughly 75,000 refugees were admitted annually. Trump sought to close down the entire program. The Biden administration restored the prior level only after a public campaign. Biden’s initial refugee plan, 15,000 a year, would have been filled within the first few weeks after the collapse of Kabul.