Talk of a U.S. military strike in response to chemical weapon deployment in Syria has weighed on Middle East exchange traded funds as geopolitical tensions fuel uncertainty.

The Market Vectors Gulf States Index ETF (NYSEArca: MES) declined 7.5% and WisdomTree Middle East Dividend Fund (NYSEArca: GULF) fell 6.0% since August 26 when Secretary of State John Kerry commented on Syria’s use of chemical agents against its population. [Israel, Middle East ETFs Dragged Down by Syria Tensions]

The U.S. has threatened military action against Syria in response to the blatant disregard to human life.

“It’s not that it’s welcome, but once it gets underway, you can quantify what the situation might look like,” Mark Luschini, chief investment strategist for Janney Montgomery, said in a CNN article. “When you’re left in the dark about when it will start, what will be the result, it gives investors trepidation.”

“People hope there will just be a tactical strike and that’s it,” Mark Grant, managing director at Southwest Securities, said in a Reuters article. “But there are worries about retaliation and a wider conflict isn’t priced into the market.”

The MarketVectors MES ETF tracks the largest and most liquid companies in the Gulf Cooperation Council region, including UAE 34.8%, Qatar 26.5%, Kuwait 23.7% and Oman 9.9%.