The US is planning an aggressive response to Iran's decision to close the Strait of Hormuz, a measure intended to force the regime to re-open the strait and make concessions on its nuclear program. The Islamic Revolutionary Guards Corps (IRGC) has blocked ships from passing through the Strait Hormu, causing the United States to increase its naval crackdown on any ship linked to Iran. U.S. forces will board Iran-linked oil tankers and seize commercial ships sailing in international waters, according to a report in The Wall Street Journal. The IRGC's statement came as two Indian-flagged ships were attacked while trying to pass through the Strait. The United Kingdom Maritime Trade Operations reported that one tanker was fired upon by two Iranian gunships and another container ship was hit by an unknown projectile. The blockade costs Iran an estimated $435 million per day.