Manama, July 22 -- Commercial shipping through the Strait of Hormuz fell to its lowest level in three weeks on Tuesday as continued Iranian attacks prompted many international ship operators to avoid the strategic waterway.

According to the Joint Maritime Information Center (JMIC) in Bahrain, a multinational maritime security partnership, the number of vessels transiting the strait dropped sharply despite repeated assurances from Washington that the route remains open.

CBS News tracked only three commercial vessels transiting the strait on Tuesday, which included two cargo ships and the Chinese-owned oil tanker Hsin Ocean.

Shipping activity has also shifted away from the US-backed southern transit corridor, which runs close to Oman's coa...