KIEV, Ukraine (AP) — Ukraine’s new president on Saturday called for pro-Russian rebels in the country’s east to lay down their arms and welcomed dialogue with the insurgents, but said he wouldn’t negotiate with those he called “gangsters and killers” and struck a defiant tone on the Russian-annexed Crimean Peninsula.

Petro Poroshenko’s inaugural address after taking the oath of office in parliament gave little sign of a quick resolution to the conflict in the east, which Ukrainian officials say has left more than 200 people dead.

He also firmly insisted that Crimea, the Black Sea peninsula annexed by Russia in March, “was, is and will be Ukrainian.” He gave no indication of how Ukraine could regain control of Crimea, which Russian President Vladimir Putin has said was allotted to Ukraine unjustly under Soviet leader Nikita Khrushchev.

Hours after the speech, Putin ordered security tightened along Russia’s border with Ukraine to prevent illegal crossings, Russian news agencies said. Ukraine claims that many of the insurgents in the east have come from Russia; Poroshenko on Saturday said he would offer a corridor for safe passage of “Russian militants” out of the country.

Rebel leaders in the east dismissed Poroshenko’s speech.

“At the moment it’s impossible for him to come (to Donetsk for talks),” said Denis Pushilin, a top figure in the self-declared Donetsk People’s Republic. “Perhaps with security, a group, so people won’t tear him to pieces.”

Poroshenko offered amnesty to rebels who “don’t have blood on their hands.” But “I don’t believe it,” said Valery Bolotov, the insurgent leader in the Luhansk region. Rebels in both Luhansk and Donetsk have declared their regions independent.

The new president promised “I will bring you peace,” but did not indicate whether Ukrainian forces would scale back their offensives against the insurgency, which Ukraine says is fomented by Russia.

Russia has insisted on Ukraine ending its military operation in the east. Ambassador Mikhail Zurabov, representing Moscow at the inauguration, said Poroshenko’s statements “sound reassuring,” but “for us the principal thing is to stop the military operation,” adding that the insurgents should also stop fighting in order to bolster the delivery of humanitarian aid, RIA Novosti reported.

As president, the 48-year-old Poroshenko is commander-in-chief of the military and appoints the defense and foreign ministers. The prime minister is appointed by the parliament.

Poroshenko, often called “The Chocolate King” because of the fortune he made as a confectionery tycoon, was elected May 25. He replaces Oleksandr Turchynov, who served as interim president after Russia-friendly president Viktor Yanukovych fled the country in February after months of street protests against him.