Dhaka, May 21 -- The US State Department has announced a visa ban on owners, executives and senior officials of India-based travel agencies it accused of "knowingly facilitating illegal immigration to the United States."The Monday statement by department spokesperson Tammy Bruce did not mention any details on those hit by the visa restrictions, including their names or the names of the travel agencies they represent. The statement also did not mention how "illegal immigration" to the US was being facilitated.What do we know about the ban?The State Department said its Consular Affairs and Diplomatic Security Service mission in India has identified those "engaged in facilitating illegal immigration and human smuggling and trafficking operat...