"We are mobilising, we are preparing to react to foreign aggression," he said.
Although he paid tribute to Ukraine's interim leaders "who stood side by side with us on the barricades", Tarasenko also sought to distance Pravy Sektor from the pro-EU team led by interim president Oleksandr Turchynov.
"There has been no reset of power. Only the names in the government offices have changed," he was quoted as saying.
"Our struggle is entering a peaceful phase, a political phase and that is why we are going into politics," he said.
Tarasenko said a Pravy Sektor congress to transform the movement into a political party would take place on March 15.
Russia this month opened a criminal investigation against Yarosh for incitement to extremism and terrorism and is seeking his arrest.