cairo egyptian military jet destroy 10 vehicles carry weapons ammunition smuggle goods near country western desert border libya army say saturday egypt porous border libya long headache security force weapons flow across frontier attack police last month claim new militant group highlight security challenge western desert air force deal destroy completely kill elements inside army statement say without give date operation egypt security force battle stubborn islamic state insurgency northern sinai region militants kill hundreds police troop since 2014 attack start increase egyptian force destroy arm smugglers vehicles libya border