Oil prices tumbled $4 a barrel on Monday after US President Donald Trump held off on a fresh attack on Iran, seeking to reach a quick deal that would halt Tehran’s nuclear ambitions and reopen the Strait of Hormuz. Brent crude futures slid $4.08, or 4.64%, to $83.85 by 2352 GMT while US West Texas Intermediate crude was at $80.66 a barrel, down $4.01, or 4.74%. Both contracts jumped more