Operation Defensive Shield (Hebrew: מִבְצָע חוֹמַת מָגֵן Mīvtzāh Ḥōmat Māgēn) was a 2002 Israeli military operation in the Israeli-occupied West Bank during the Second Intifada. Lasting for just over a month, it was the largest combat operation in the territory since the 1967 Arab–Israeli War.

The operation began with an Israeli incursion into Ramallah, where Yasser Arafat was placed under siege at his compound. This was followed by successive incursions into the six largest West Bank cities and their surrounding localities. Israel's military moved into Tulkarm and Qalqilya on April 1, into Bethlehem on April 2, and into Jenin and Nablus on April 3. From April 3 to 21, Israel enforced strict curfews on the Palestinian populace of the West Bank and restricted movements of international personnel, including prohibiting entry to humanitarian and medical personnel and human rights monitors and journalists.

In May 2002, Israel withdrew from Palestinian cities in the West Bank, but maintained cordons of troops around certain towns and villages, and also continued carrying out raids on Palestinian-populated areas.

According to a report by the United Nations: "Combatants on both sides conducted themselves in ways that, at times, placed civilians in harm's way. Much of the fighting during Operation Defensive Shield occurred in areas heavily populated by civilians and in many cases heavy weaponry was used."

The Israeli–Palestinian conflict escalated during the Second Intifada. In January and February 2002, 71 people were killed on all sides during attacks from Palestinian terrorists and the Israeli army. March and April 2002 saw a dramatic increase in attacks against Israelis by Palestinian militants such as Hamas, Islamic Jihad and the Fatah-affiliated Al-Aqsa Martyrs' Brigades. In addition to numerous shooting and grenade attacks, fifteen suicide bombings were carried out in March, an average of one suicide bombing every two days. March 2002 became known in Israel as "Black March". The large number of attacks severely disrupted daily life in Israel.

The first wave of Israeli incursions took place between 27 February and 14 March. Following nine attacks by Palestinian militants between March 2–5, the Israeli cabinet decided to massively expand its military activity against these groups. On March 5, while talking with reporters in the Knesset cafeteria, Israeli Prime Minister Ariel Sharon, pointing to the bloodiest week against Israelis since the start of the Second Intifada, explained the cabinet's decision: "The Palestinians must be hit, and it must be very painful. ... We must cause them losses, victims, so that they feel a heavy price."

Palestinian attacks continued, with suicide bombings on 9 March (see Café Moment bombing), 20 March, and 21 March. Shooting and grenade attacks also continued to occur in Israel and Israeli settlements. On 27 March, a suicide attack occurred in Netanya, where 30 people were killed in the Park Hotel while celebrating Passover. The event became known as the Passover massacre. The following day, a Palestinian gunman infiltrated the Israeli settlement of Elon Moreh and killed four members of the same family.

On March 29, the Israeli government announced Operation Defensive Shield, terming it a large-scale counter-terrorist offensive. The Israel Defense Forces (IDF) issued emergency call-up notices for 30,000 reserve soldiers, the largest call-up since the 1982 Lebanon War. The same day, two Israelis were stabbed in the Gaza settlement of Netzarim. Two suicide bombings occurred the next day, and another one took place the day after that.^{[citation needed]}