Russian Jets Keep Crossing Into Ukraine

US defense officials said today that Russian fighter jets flew into Ukrainian airspace a handful of times over the last 24 hours, in what one called a continued provocation of the heightened tensions in the region. The officials said it's not clear what the intent was, but the aircraft could have been testing Ukrainian radar or making a show of force. Col. Steve Warren, a Pentagon spokesman, confirmed the flights, adding that the US is calling on the Russians "to take immediate steps to de-escalate the situation."

The flights come as Russia increases military exercises along the Ukraine border, including moving a broad array of fixed wing and rotary aircraft, infantry, and armored troops. The exercises inflame worries about a potential Russian military incursion into Ukraine. The West has threatened additional sanctions against Russia over its annexation of Ukraine's Crimean region in March and the ongoing escalation of military operations along the border. Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, spoke with his Russian counterpart, Gen. Valery Gerasimov, yesterday, but officials were not able to provide details of the conversation. (See how Ukraine's prime minister is amping up the rhetoric.)