Activists on board a flotilla of vessels sailing toward Gaza said they were prepared for the Israel navy to intervene as they approached the besieged Palestinian territory on Wednesday after a tense night in the Mediterranean Sea.

The Global Sumud Flotilla, with Greta Thunberg aboard, consists of about 50 boats and 500 activists and is carrying a symbolic amount of aid. It has remained undeterred in its mission to break the Israeli blockade of the coastal strip and reach Palestinians.

Israel pressed its offensive in Gaza on Wednesday, with at least 16 Palestinians reported killed across the strip as Hamas mulled its response to U.S. President Donald Trump's peace plan for the embattled territory.

The United States will regard "any armed attack" on Qatari territory as a threat to Washington and will provide the Gulf Arab state with security guarantees, the White House said on Wednesday, after an Israeli strike on the country last month.

"In light of the continuing threats to the State of Qatar posed by foreign aggression, it is the policy of the United States to guarantee the security and territorial integrity of the State of Qatar against external attack," said an Executive Order signed by U.S. President Donald Trump on Monday and released on Wednesday.

Israeli Prime Minister Benjamin Netanyahu may have finally outmaneuvered Hamas.

After facing months of genocide accusations, pariah status and global pressure to halt the war in Gaza, Netanyahu has agreed on a ceasefire plan with U.S. President Donald Trump.

Israel's defense minister on Wednesday said the military would tighten its encirclement of Gaza City, issuing a final warning for residents there to flee south.

"This is the last opportunity for Gaza residents who wish to do so to move south and leave Hamas operatives isolated in Gaza City," Israel Katz said in a statement shared with Israeli media. "Those who remain... will be considered terrorists and terrorist supporters."

The Israeli military said security forces killed an assailant who carried out a ramming attack in the occupied West Bank on Tuesday, which medics said injured two people.

U.S. President Donald Trump on Tuesday gave Hamas an ultimatum of "three or four days" to respond to his plan to end the war in Gaza, as the militant group reviewed the proposal backed by Israel.

A Palestinian source close to Hamas told AFP on Tuesday that the group is reviewing U.S. President Donald Trump's proposal for ending the Gaza war, which is backed by the Israeli prime minister.

"Hamas has begun a series of consultations within its political and military leaderships, both inside Palestine and abroad," the source, speaking on condition of anonymity, said.

Islamic Jihad, a Palestinian militant group fighting alongside Hamas in Gaza, on Monday slammed U.S. President Donald Trump's plan to end the war, saying it would fuel further aggression against Palestinians.

"It is a recipe for continued aggression against the Palestinian people. Through this, Israel is attempting — via the United States — to impose what it could not achieve through war," the group said in a statement. "Therefore, we consider the American-Israeli declaration a formula for igniting the region."

Egypt, Jordan, Saudi Arabia, Qatar, the United Arab Emirates, Turkey, Indonesia and Pakistan on Tuesday welcomed U.S. President Donald Trump's peace plan for Gaza.

The eight Arab and Muslim nations said in a joint statement that they "welcome the role of the American president and his sincere efforts aimed at ending the war in Gaza" and "affirm their readiness to engage positively and constructively with the United States and the parties toward finalizing the agreement and ensuring its implementation".