About 100 Ukrainian troops will head to Oklahoma's Fort Sill as soon as next week to begin training on the Patriot missile defense system, the Pentagon announced Tuesday.Ukraine has long sought the Patriot surface-to-air guided missile defense system because it can target aircraft, cruise missiles and shorter-range ballistic missiles. During his late December visit to the U.S., Ukrainian President Volodymyr Zelenskyy said the battery would make a significant difference in bolstering Kyiv's defenses against Russia's invasion.