Many South Korean workers were sent to the U.S. on questionable documents despite their misgivings and warnings about stricter U.S. immigration enforcement before last week¡¯s raid on a Hyundai site, according to workers, officials and lawyers.

For years, South Korean companies have said they struggle to obtain short-term work visas for specialists needed in their high-tech plants in the United States, and had come to rely on a grey zone of looser interpretation of visa rules under previous American administrations.

When that changed in the early days of U.S. President Donald Trump¡¯s second term, some workers were denied entry to the United States under statuses that did not fully allow work, according to interviews with more than a dozen workers from various companies, government and company officials, and immigration lawyers.