Secretary of State John Kerry gestures as he speaks during a joint news conference with Colombian Foreign Minister Maria Holguin at the State Department,
Secretary of State John Kerry gestures as he speaks during a joint news conference with Colombian Foreign Minister Maria Holguin at the State Department, Friday, in Washington, as Kerry opens a fourth round of the U.S.-Colombia High-Level Partnership Dialogue. (AP Photo/Carolyn Kaster)

WASHINGTON - Secretary of State John Kerry calls Russia's military incursion into Ukraine 'an incredible act of aggression" and says President Vladimir Putin has made "a stunning, willful" choice to invade another country.

Kerry says Russia should respect the democratic process through which the Ukrainian people ousted their pro-Russian president and assembled a new government.

Kerry is raising the possibility of boycotting the June meeting of the Group of Eight leading industrialized countries in Sochi, Russia.

He's also discussing visa bans, asset freezes, and trade and investment penalties.

Kerry said he spoke with foreign ministers for G-8 and other nations on Saturday, and says everyone is prepared 'to go to the hilt" to isolate Russia.

Kerry was interviewed Sunday on CBS, ABC and NBC news shows.