"I'm not afraid of Israel," the 35-year-old father of six said while seated on floor cushions in his home in the Zeitoun neighbourhood of Gaza City, his children occasionally peeking their heads around the door.
The member of the leftist Democratic Front for the Liberation of Palestine (DFLP) said preparations for another war have included rebuilding attack tunnels destroyed by Israel two years ago.
As a wave of Palestinian stabbings, shootings and car-rammings have shaken the West Bank and Israel, the Gaza Strip has remained relatively calm.
But increasingly belligerent rhetoric from both Israel and Hamas, the Islamist group that rules Gaza, along with the reconstruction of tunnels the Jewish state says could be used to attack it, have renewed fears of yet another conflict in the enclave still recovering from the 2014 war.
In many ways, another confrontation with the Israeli military would be the last thing the Gaza Strip needs -- there have been three since 2008.
Around 100,000 people are still displaced and the unemployment rate is among the world's highest.
An Israeli blockade has been in place for nearly a decade, tightly restricting the movement of goods and the 1.8 million Gazans.
Beyond that, a more radical strain of Islam has taken root, with Hamas seeking to limit the influence of Salafist jihadists who sympathise with the Islamic State group and who have claimed responsibility for recent rocket fire toward Israel.
All of it deeply concerns those involved in rebuilding Gaza.
Robert Piper, the UN's deputy special coordinator for the Middle East peace process, told AFP after a recent visit that it "remains on a frankly disastrous trajectory of de-development and radicalisation, as far as I can tell".
The deadly January 26 collapse of a tunnel belonging to Hamas's armed wing, the Ezzedine al-Qassam Brigades, as well as another on February 2 drew fresh scrutiny of the movement's intentions.
The tunnels have been used to store weapons and stage attacks in the past, with Hamas officials saying they are necessary to defend against Israel's firepower.
In 2006, a group of militants entered Israel through a tunnel, seized Israeli soldier Gilad Shalit and smuggled him back to Gaza, resulting five years later in a prisoner exchange that saw more than 1,000 walk out of Israeli jails.
Last month's collapse killed seven Hamas militants who were hailed as heroes, with Ismail Haniya, Hamas's chief in the enclave, giving a speech at their funeral at Gaza City's main mosque.
"East of Gaza City, underground heroes build tunnels" along the Israeli border, while west of the city they are "testing rockets every day", said Haniya.
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A Hamas official later called them "defensive tunnels for the protection of our people in the face of any Israeli aggression".
Israeli Prime Minister Benjamin Netanyahu responded with his own threats.
"If we are attacked from tunnels from the Gaza Strip, we will take very strong action against Hamas, much stronger" than in 2014, he said.
Violence since October has already killed 26 Israelis and 164 Palestinians.
Most of the Palestinians were killed while carrying out attacks, while others were shot dead during clashes and demonstrations.
While violent protests have broken out along the Gaza border, with a number of Gazans shot dead by Israeli forces during clashes, the strip has so far played only a limited role in the unrest.
Some analysts say Hamas would prefer to rebuild rather than face another war.
But it cannot remain completely on the sidelines during what many Palestinians are calling a new "intifada", or uprising, in the West Bank.
'Started with stones'
It must also contend with pressure from Salafists, though the threat has so far been seen as limited.
Among the narrow streets of Shati refugee camp near the Gazan shoreline, a man claiming to lead a Salafist group said he could see himself travelling to Syria or Iraq to fight with the Islamic State.
Sporting a thick beard and an olive green jacket, he told AFP he believed Hamas's version of Islam was not pure enough and that he was among those who had split from Al-Qassam Brigades to join the Salafists.
"Our jihad is to have Allah's religion on the ground," he said.
The militant said Salafists had fired rockets at Israel in defiance of a truce that ended the 2014 war in revenge for Hamas's arrest of its members.
Hamas was said to have arrested around 100 of them last year.
But for those like Mohammed, the Gazan who has finally moved back into his home, the enemy is Israel.
He said he received a warning phone call from the Israeli military before his home was hit in 2014 that gave him minutes to evacuate the family.
"We started with stones," he said defiantly, referring to the first intifada in 1987-1993. "Now we have rockets. As long as Israel stays on my land, the resistance will continue."