By Alexander Cornwell and Jonathan LandayMarch 17 (Reuters) - U.S. President Donald Trump accused some Western allies of ingratitude after several countries rebuffed his demand to send warships to escort oil tankers through the Strait of Hormuz, as Iran continued to target oil facilities in the Gulf.The U.S.-Israeli war on Iran is in its third week with no end in sight. The critical Strait of Hormuz, through which 20% of the world's oil and liquefied natural gas flow, remains largely closed off,...