Six people were killed in an attack in Jerusalem on Tuesday, and within hours Israel's government issued an uncompromising ultimatum to Hamas, saying it would intensify air and ground strikes on the Gaza Strip until the militant group accepted Israeli conditions for a halt to the fighting.

"We will unleash a hurricane of strikes until Hamas accepts our terms," Defense Minister Yoav Gallant said in televised remarks from Tel Aviv, framing the operation as necessary to degrade Hamas's military capacity and secure the release of hostages taken in earlier raids. Israeli officials said the ultimatum demands the disarmament of key Hamas units and immediate negotiations on the terms of a ceasefire, and they set a 48-hour window for compliance. Military spokesmen warned that failure to yield would trigger "the most intense phase" of an already prolonged campaign.

The announcement followed the Jerusalem attack, in which Israeli police said six civilians died and several others were wounded. Israeli authorities have identified the assailants as members of a small militant cell they say has ties to Gaza-based groups. Hamas has not claimed responsibility for the Jerusalem attack but issued a defiant response through a spokesman, saying Palestinian factions "will not bow to threats" and accusing Israel of using the incident to justify a broader assault on Gaza.

International actors swiftly reacted to the escalation. Spain, which has been among the more vocal European critics of Israeli operations in Gaza, urged Madrid and other EU capitals to step up diplomatic pressure. "We call on Israel to exercise maximum restraint and to avoid actions that would amount to collective punishment of the Palestinian population," Spain's foreign ministry said in a statement, urging immediate humanitarian access to Gaza. Prime Minister Pedro Sánchez's government has faced domestic pressure to push the EU toward a stronger, unified position.

In Washington, U.S. officials said they were in close contact with Israeli counterparts and reiterated support for Israel's right to self-defense while warning against steps that could exacerbate civilian suffering. "We urge careful calibration to avoid further humanitarian catastrophe," a senior U.S. official told reporters, speaking on the condition of anonymity.

The United Nations and human rights groups expressed alarm at the prospect of a major intensification. UN Secretary-General António Guterres called for "the protection of civilians and full compliance with international humanitarian law," noting that Gaza's densely populated urban environment makes any large-scale military operation particularly perilous for non-combatants.

Analysts say the escalation risks shattering fragile diplomatic efforts and could entangle regional actors. Egypt and Qatar have historically mediated between Israel and Hamas; both have signaled concern and urged de-escalation. The European Union's foreign policy chief has convened an emergency meeting of envoys to discuss possible responses, including calls for an immediate humanitarian pause.

Within Israel, the government faces intense domestic pressure to respond forcefully, fueled by public outrage and grief over the Jerusalem attack. But international legal experts warn that an unrestrained campaign could expose Israeli commanders and political leaders to accusations of disproportionate force or failure to take feasible precautions to protect civilians.

As night fell over Gaza and Jerusalem, the prospect of a sustained "hurricane" of strikes cast a long shadow over already fragile prospects for peace, underscoring how a single attack can rapidly reshape regional diplomacy and raise fraught questions about law, morality and the protection of civilians.