MOSCOW (AP) — Ukraine's General Prosecutor's Office has launched a criminal investigation of 20 senior Russian officials, including the Russian defense minister.

Ukraine's Prosecutor General Yuri Lutsenko said Monday they are suspected of involvement in crimes against Ukraine's national security. He said Ukrainian authorities plan to seek international warrants for their arrests.

The list includes Russian Defense Minister Sergei Shoigu and two of his deputies, Kremlin economic adviser Sergei Glazyev, a former presidential envoy to Crimea, and other top officials.

Russia and Ukraine have been in a tug-of-war since Moscow annexed Ukraine's Crimean Peninsula in March 2014 and backed a pro-Russian insurgency in eastern Ukraine. Tensions have spiked after Russia said that it had busted a group of Ukrainian saboteurs in Crimea, a claim Ukraine has denied.