KINGSTON, Jamaica — Global oil prices fell below US$80 a barrel on Tuesday as anexpected agreement between the United States (US) and Iran raised hopes that more crude could return to the market and ease pressure on fuel-importing countries such as Jamaica. Brent crude, the international benchmark used to price much of the oil traded worldwide, fell to its lowest level in about three months. US West Texas Intermediate crude also declined as traders assessed the prospects for increased shipments from the Middle East.