Israeli tanks moved into the occupied West Bank on Sunday for the first time in decades in what Palestinian authorities called a "dangerous escalation," after the defense minister said troops will remain in parts of the territory for a year and tens of thousands of Palestinians who have fled cannot return. Associated Press journalists saw several tanks move along unpaved tracks into Jenin, long a bastion of armed struggle against Israel. Israel is deepening its crackdown on the Palestinian territory and has said it is determined to stamp out militancy amid a rise in attacks. It launched the offensive in the northern West Bank on Jan. 21 -- two days after the current ceasefire in Gaza took hold -- and expanded it to nearby areas.