Oil prices jumped by nearly $2 a barrel on Monday, after the United States launched an attack on an Iranian island in the Strait of Hormuz, prompting a response from Tehran, as the conflict in the Middle East entered its sixth month. Brent crude futures rose $2.08, or 2.36%, to reach $90.18 per barrel by 04:17 GMT, while the price of US West Texas Intermediate crude reached $85.07 per barrel, an increase of $1.67, or 2%.