Israel and Palestinian militants in the blockaded Gaza Strip have been exchanging fire in the worst escalation since a 2014 war. Here's a description of where the situation stands:
How did this round begin?
The latest round of violence began on Sunday, when Israeli special forces were exposed operating inside the Gaza Strip. In an ensuing clash, an Israeli officer and seven Palestinian militants were killed, prompting Hamas to vow revenge.
Israel said the covert operation was an intelligence-gathering mission.
Its timing has raided questions since progress had been made in recent weeks toward ending months of unrest along the Gaza-Israel border, but the Israeli military said it was necessary to defend the country.
Palestinian militants responded with heavy fire on southern Israel, launching nearly 400 mortar rounds and rockets that wounded 27 people and killed one -- a Palestinian living in southern Israel.
An anti-tank missile also hit a bus that Hamas says was being used by Israeli soldiers. A soldier was severely wounded.
Israel hit back with widespread strikes on Hamas and Islamic Jihad targets, killing six Palestinians and wounding 25.
Israel says it has struck around 150 targets across the Palestinian enclave, including Hamas's Al-Aqsa TV building and an internal security building in Gaza City.
Efforts to prevent escalation
UN Middle East envoy Nickolay Mladenov said he was working with Egypt so "Gaza steps back from the brink," and called for restraint on both sides.
Israeli officials would not confirm reports on ceasefire talks, as members of the security cabinet -- the body authorised to declare war -- convened in Tel Aviv.
Neither side is seen as wanting another war, but the violence threatened to spin out of control.
Israeli military spokesman Jonathan Conricus said they had "the intelligence and capabilities to strike a very wide range of military targets that belong to Hamas."
Hamas's armed wing warned it would expand its targets if Israeli strikes continued.
The Israeli army estimated there were 20,000 projectiles in Gaza that could be fired.
Months of unrest
The latest round of violence came after months of deadly unrest along the Gaza-Israel border, but there had been progress toward restoring calm in recent weeks.
Israel had allowed Qatar to bring $15 million into Gaza for salaries as well as fuel to ease an electricity shortage, as part of understandings aimed at calming the border, where protests have triggered frequent clashes since March 30.
Israeli Prime Minister Benjamin Netanyahu defended the move, saying he wanted to avoid war if it was not necessary.
As a result, border protests had been calmer over the past couple weeks.
At least 233 Palestinians in Gaza have been killed by Israeli fire since March 30, the majority shot on the border, while others have died in Israeli strikes.
Two Israeli soldiers have been killed in that time.
Egypt and the United Nations had been brokering indirect negotiations for a long-term truce with Israel, against which Hamas has fought three wars since 2008.
Gaza in crisis
Gaza is ruled by Hamas, blacklisted as a terrorist movement by the European Union and the United States.
Israel maintains a crippling blockade of the Palestinian enclave to isolate Hamas and prevent it from building up its military capabilities.
Hamas seized control of Gaza in 2007 from forces loyal to the West Bank-based Palestinian Authority, which has been seeking ways to regain power over the small territory.
Multiple efforts to reconcile the Palestinian factions have failed, and with an unemployment rate of 53 percent, Mladenov recently warned of a humanitarian crisis in Gaza, which he said was "imploding."