[International oil prices open lower, gold and silver rise after U.S. 'lightning strike' on Venezuela] WTI crude oil futures opened 1% lower in early Asian trading on Monday, while Brent crude oil futures prices once fell 1.2% to $60 per barrel. Spot gold rose 0.5%, and spot silver rose 1%. U.S. stock futures opened slightly higher in early Asian trading, with S&P 500 futures up 0.08% and Nasdaq futures up 0.17%. U.S. Treasury futures showed little change at the open.