The US is sending more Patriot defense systems to the Middle East. They cost $1.1 billion each.

• The Patriot is a missile air defense system that can reach aerial targets up to 66,000 feet.
• It's a highly sought-after defense system that costs $1.1 billion each.
• The US has recently doubled the number of Patriot batteries in the Middle East, WSJ reported.

The US has sent more of its valuable surface-to-air missile defense systems, known as the Patriot battery, to the Middle East following attacks on American troops in Iraq and Syria in recent weeks, The Wall Street Journal reported.