Iraq has made the first payment in a deal to buy 18 US F-16 fighter jets worth a total of about $3bn (£1.9bn), the US state department has said.The planes, which are not expected to be delivered until next year, are to protect the country's air space.There are currently some 44,000 US troops in Iraq, which are due to leave by the end of this year.US and Iraqi officials said the purchase of the jets would provide the basis for Iraq's air sovereignty."The air force is considered a vital factor to protect Iraq's sovereignty and security against external threats," Iraqi government spokesman Ali al-Dabbagh said."Iraq needs to build its air force and to depend on its own capabilities to defend the skies instead of asking other countries to do so - especially if we know that the US forces will leave at the end of this year."Mr al-Dabbagh said $1.4bn has already been transferred as a partial payment. From / BBC