For more than a year, Israel and the network of Qassam-launching Gaza militants have been playing an increasingly volatile game of chicken.
Gaza militants fire daily volleys of crude rockets into southern Israel until they eventually maim or kill an Israeli civilian.
Israeli military air strikes kill rocket launchers and militants driving through Gaza City. The attacks target Hamas bases and empty Palestinian Authority offices.
The two sides hurtle towards a direct confrontation - until one side backs down and things cool off. For a while.
This week, the two sides might have reached a tipping point.
For the first time in nine months, one of the Qassams hit with deadly force.
On Wednesday, a Qassam killed a 47-year-old father and student at Sapir College in southern Israel. The next day, Gaza militants fired a barrage of slightly more advanced rockets that hit Ashkelon, the largest city near the Gaza Strip.
Ashkelon responded by turning on the city's early warning system, which will send residents scrambling for bomb shelters whenever the Israeli military picks up the launch of a rocket from Gaza, even if they are heading for a nearby town.
After the student was killed, Israeli air strikes hit the empty Interior Ministry building and the vacant office of deposed Hamas PM Ismail Haniyeh. The attacks ravaged a medical clinic, killed seven young kids, including a baby and four boys playing soccer.
As they have before, Israeli defense officials said the rocket fire would not be tolerated. But this week they took some new steps to prepare for a possible invasion. The military moved artillery units and a small number of tanks to the Gaza border.
There are still widespread reservations within the Israeli government about a major ground invasion.
And the US is likely to frown upon any major Israeli military operation that comes on the eve, or during, Secretary of State Condoleezza Rice's visit to the region next week.
But with each successive round of chicken, the stakes get higher, frustration grows on both sides and Israeli restraint erodes.
If Hamas decides to keep its sites on Ashkelon and Israel keeps sending forces to the Gaza border, it may not be too long before the Israeli military concludes that an invasion is the best option.