JERUSALEM >> Israel announced Sunday that it was expanding its weekslong military operation against armed Palestinian groups in the occupied West Bank and had deployed tanks in the territory’s north for the first time in two decades.

Adding to the escalating tensions, Israeli Defense Minister Israel Katz said that tens of thousands of Palestinian residents who have left the centers of militancy targeted by the Israeli operation and are displaced within the West Bank will not be allowed to return to their homes.

Israel’s actions came after bombs exploded on three buses on Thursday night in different parking depots in the suburbs of Tel Aviv, Israel. At least one other explosive device was discovered and dismantled. Police are still investigating, but they said the devices resembled improvised bombs made in the West Bank.

The buses had emptied of passengers before the explosions, which caused no injuries. But the blasts jarred Israelis, recalling the deadly bus bombings of the mid-1990s and early 2000s, and the country was put on a terrorism alert.

Prime Minister Benjamin Netanyahu immediately called for “a massive operation” in the West Bank, after weeks of what the Israeli military describes as a campaign to root out militant groups and prevent terrorist attacks on Israeli civilians. Israel has shifted its attention to the centers of militancy in the northern West Bank as its campaign against Hamas in the Gaza Strip has wound down.

Speaking at the military’s officers’ training school Sunday, Netanyahu said troops would remain in the West Bank “as long as needed” and that sending tanks in for the first time in decades meant one thing: “We are fighting terrorism with all means and everywhere.”

On Friday, Netanyahu and Katz made rare visits to an area known as the Tulkarem refugee camp, one of the crowded neighborhoods where refugees who fled or were expelled during the 1948 war that surrounded Israel’s creation and their descendants were housed.

The area, one of the focuses of Israel’s offensive, is nominally under the control of the Palestinian Authority, a body that exerts limited power in parts of the West Bank.

The Israeli military operation across several West Bank cities has displaced roughly 40,000 Palestinians from their homes, in what experts say is the biggest displacement of civilians in the territory since the Arab-Israeli war of 1967.

The military denies that there have been any forced evacuations in the West Bank. A military spokesperson, Lt. Col. Nadav Shoshani, said recently that in some cases people had been ordered to leave specific buildings close to militant hideouts, but that people were generally allowed to move around unimpeded.

Roughly 3,000 people have been able to return to al-Faraa camp, near Tubas. But Palestinians have said they fear a veiled Israeli attempt to permanently displace Palestinians from their homes and exert greater control over areas administered by the Palestinian Authority.

Katz said in a statement Sunday that 40,000 Palestinians had left two refugee camp areas in Tulkarem and a third one in Jenin, and that they were now “empty of residents.” Katz added that UNWRA, the main United Nations agency providing assistance in the camps, was no longer functioning there.

“I have instructed the military to prepare for a long stay over the coming year in the purged camps and not to allow residents to return and terrorism to grow back,” he added.

The Palestinian Authority’s Ministry of Foreign Affairs issued a statement Sunday saying it considered Katz’s statements, along with the deployment of tanks and what it described as the intimidation of unarmed civilians, to be “a dangerous escalation.” It said Israel was trying to entrench a policy of forced displacement in the West Bank.

The ministry called for international intervention to curb what it described as Israel’s “unchecked aggression,” and “to compel Israel to halt its assault on our people and their fundamental right to remain on their land.”