* Graphic: World FX rates in 2017 http://tmsnrt.rs/2egbfVh
* Metals surge, zinc at highest in a decade
* U.S. political uncertainty weighs on stock prices
* Dollar struggles, yen favored
* Investors wary as U.S., South Korea begin military drills
* Markets eye Fed's central bank gathering in Jackson Hole (Updates to U.S. market open, new throughout, changes dateline, previous LONDON)
NEW YORK, Aug 21 (Reuters) - A gauge of world stock indexes touched a 5-1/2-week low on Monday as Wall Street opened lower, though metals prices dazzled with zinc at its highest in a decade, copper hitting a nearly three-year peak and iron ore gaining nearly 15 percent in the last three sessions.
U.S. stocks were on the edge of a fifth straight day of losses as tensions simmered between the United States and North Korea. Doubts also lingered about the ability of U.S. President Donald Trump's administration to push through a pro-business agenda of tax cuts and infrastructure spending.
The Dow Jones Industrial Average fell 2.14 points, or 0.01 percent, to 21,672.37, the S&P 500 gained 0.94 points, or 0.04 percent, to 2,426.49 and the Nasdaq Composite dropped 11.41 points, or 0.18 percent, to 6,205.11.
European stocks fell as geopolitical jitters trickled over from Asian trading with investors shedding risky assets as joint U.S. and South Korean military drills began.
Analysts said market participants were also awaiting an upcoming speech from Trump on U.S. strategy in Afghanistan later in the evening.
"Some people are a little apprehensive and not sure whats going to be said," said Ian Winer, head of equities at Wedbush Securities in Los Angeles.
Additionally, Winer said, without much in the way of U.S. economic data or other headlines, "its a quiet Monday and people are still feeling the effects of last week. Now that earnings are over theres just not a whole lot of catalysts."
MSCI's all-country world index was flat after earlier touching its lowest since July 12.
Chinese and emerging market shares rose, boosted by mainland China shares, which added to gains following the Shanghai stock index's biggest weekly advance in four months last week.
Hopes for Chinese infrastructure spending and a potential demand boost down the road from electric cars helped zinc hit its highest since October 2007 at $3,180.50 a tonne.
Copper rallied to $6,623 a tonne, its highest since November 2014.
China's iron ore futures soared more than 4 percent, fueled by concerns of shortages and before curbs on futures purchases which are expected to come into force in the next few months.
Gold prices turned higher, spurred by safe-haven demand and doubts about Trump ability to enact his policy proposals.
The geopolitical fears also helped boost the Japanese yen against the dollar. The U.S. currency has fallen for four straight sessions against the safe-haven yen, which is sought for its liquidity in times of market stress.
The dollar was last down 0.3 percent against the yen at 108.85 yen.
"After testing support at 108.50 three times over the past month, dollar/yen appears to have found a base at this level and the key question this week will be whether the dollar can stage any sort of counter-trend rally ahead of the Jackson Hole symposium this week," said Boris Schlossberg, managing director of FX strategy at BK Asset Management in New York.
U.S. Treasury yields were little changed ahead of the Federal Reserve's conference in Jackson Hole, Wyoming at the end of the week.
Investors were looking to European Central Bank chief Mario Draghi's comments at the event, although sources told Reuters last week he would not deliver any fresh policy messages.
Fed Chair Janet Yellen's keynote speech will also be scoured for clues on the U.S. central bank's next move.
The benchmark U.S. 10-year Treasury note was little changed from its late Friday closing levels, yielding 2.20 percent.
Oil prices fell after big gains on Friday, which had been triggered by data showing U.S. drillers cut the number of oil rigs.
U.S. crude futures fell to $47.87 per barrel, while Brent futures slipped to $51.88 per barrel, helping drag stock prices.
(Additional reporting by Hideyuki Sano in Tokyo; Editing by Matthew Mpoke Bigg and Meredith Mazzilli)