Two Palestinians believed to be militants were killed in an Israeli strike on northern Gaza early on Wednesday, medics said, just hours after a blunt warning from Israel's prime minister.
Ashraf al-Qudra, a spokesman for the Hamas-run health ministry, named the two as Ahmad al-Zaanin, 21, and Mohammed al-Zaanin, 23, and said they died when a missile struck their car as they were driving around the northern town of Beit Hanun.
Witnesses said the two belonged to Islamic Jihad's armed wing the Al-Quds Brigades, but there was no immediate confirmation of this from the group itself.
The Israel military confirmed the attack, saying it was a targeted strike against Ahmad al-Zaanin, describing him as "a senior operative in the PALP terror organisation" who was responsible for recent anti-Israeli attacks and who posed an "imminent threat" to civilian lives.
"Ahmad Zaanin was a key Popular Front for the Liberation of Palestine (PFLP) operative in the Gaza Strip who has actively planned to launch rockets at Israeli communities in the south of Israel," a military statement said.
It said he was behind rocket fire on January 15 which struck open ground shortly after the funeral of former premier Ariel Sharon.
The funeral took place at a site several kilometres (miles) from the Gaza border in an event attended by hundreds of civilians as well as Israel's top political and military leadership.
The army said Zaanin had also backed sniper attacks and the use of explosive devices against Israeli troops, describing him as a former Islamic Jihad militant.
The strike took place just hours after Israeli Prime Minister Benjamin Netanyahu threatened to teach Gaza's ruling Hamas movement a lesson "very soon" following an uptick in rocket attacks over the past month.
"We have a very clear policy. We prevent terror attacks when we identify them in the making, and we respond forcefully against whoever hurts us," Netanyahu said on Tuesday.
"This policy produced a quiet year in 2013, which was the quietest in many years. If Hamas and the terror organisations have forgotten this lesson, they will learn it again powerfully very soon."
Earlier on Tuesday, Hamas confirmed it had deployed forces in Gaza to "preserve the truce" which ended the last major confrontation in November 2012.
Over the past month, tensions have risen in and around Gaza after more than a year of relative calm.
Since December 20, six Palestinians and an Israeli have been killed in violence in and around Gaza, with militant rocket fire sparking retaliatory air strikes.
Army figures show eight rockets have struck Israeli territory since January 1, and another five were intercepted by the "Iron Dome" anti-missile system, sparking fears that a new confrontation with Gaza militants is looming.