WASHINGTON, Oct. 15 (UPI) -- A $1 billion deal to pipe natural gas to Syria from Iran announced in early October signals increasing ties between the two foes of the United States, and its path through Turkey could inflame tensions at a time when U.S.-Turkish relations are strained.

Iran plans to export about 100 billion cubic feet of natural gas to Syria every year, according to Iranian state-run media. The deal would require the gas to be transported through Turkey by pipeline, a situation that could hurt U.S. efforts to isolate the energy economy of Iran.

But Iran's ability to supply Syria with that much natural gas remains unclear. In the winter of 2006, domestic shortages forced Iran to stop major natural gas shipments to Turkey, causing Ankara to turn to Moscow for supplies. Turkey, which faces its own increasing natural gas demand, has shown interest in investing in Iran's massive South Pars field and has been importing between 100 billion and 150 billion cubic feet of natural gas from Iran since the Iran-Turkey pipeline was built in 2001.

Iran is desperate for investment needed to develop its natural gas reserves, especially the South Pars field in the Persian Gulf, estimated to be home to about 280 trillion cubic feet of natural gas. Under pressure from the United States, and more recently France, many international petroleum companies are hesitant to invest in South Pars development.

Syria holds 8.5 trillion cubic feet of natural gas, and while it is hoping to increase its production, for the time being it uses all of the roughly 250 billion cubic feet it produces annually, according to the Energy Information Administration, the data arm of the U.S. Department of Energy.