New Delhi, July 17 -- Students already in the US and holding F or J visas will have four years from the effective date of the new rule to reapply, regardless of when they arrived or how long their academic program lasts. The change is part of a sweeping overhaul by the Trump administration that replaces a decades-old policy allowing international students to remain in the country for the duration of their studies.

The new regulation introduces a fixed four-year limit for most international students and exchange visitors entering the US on F and J visas. Officials say the move is aimed at reducing visa fraud, preventing overstays and tightening immigration controls. However, universities and immigration advocates warn it could create sign...