Israel’s defense minister said Tuesday that the military will not change its tough response to Hamas-led mass protests near Gaza’s border with Israel, warning that those who approach the border are putting their lives at risk.

Avigdor Lieberman spoke near Gaza, where 18 Palestinians were killed by Israeli fire Friday, the first day of what Hamas says will be six weeks of intermittent border protests against a stifling blockade of the territory.

On Tuesday, a 25-year-old Gaza man was killed by Israeli fire as he threw stones in the area of the border fence, Gaza’s Health Ministry said.

Lieberman’s comments raised the possibility of more bloodshed this Friday, when another mass protest is expected.

The Palestinians’ ambassador at the United Nations, Riyad Mansour, appealed to the U.N. Security Council for immediate international protection for Palestinian civilians, especially in Gaza. He charged in a letter to the council that Israel has adopted “a shoot-to-kill policy” during what he called peaceful protests.

Mansour strongly backed Secretary-General Antonio Guterres’ call for an independent investigation of the killings and accused Israel of “intentionally, grossly and systematically” violating its legal obligation to protect civilians.

The international group Human Rights Watch accused Lieberman and other senior Israeli officials Tuesday of unlawfully calling for the use of live fire against Palestinian protesters who posed no imminent threat to life.

Last Friday, thousands of Palestinians marched near the border fence between Israel and Gaza, many gathering around tent encampments set up several hundred meters (yards) from the frontier. Smaller groups moved closer to the fence, throwing stones, hurling firebombs or burning tires. Israeli troops were lined up on the other side of the fence, including snipers perched on high earth embankments overlooking Gaza.

Palestinian health officials have said 18 Palestinians were killed that day, including 13 involved in the mass protest, making it the bloodiest day in Gaza since the 2014 war between Israel and the Islamic militant group Hamas.

More than 750 Palestinians were wounded by Israeli fire, according to Gaza health officials. Mansour told the Security Council the number of wounded was over 1,500, including more than 750 by live ammunition and 148 by rubber-coated steel bullets.

The Israeli military has claimed, without elaborating, that it believes the figure was overblown and that dozens, at most, were wounded by live rounds.

Israeli officials have said soldiers in the border area had orders to target the “main instigators” and those who approach the border.

In Tuesday’s violence, the military said dozens of Palestinians had participated in “riots” at four locations along the border, and troops had fired toward suspects who damaged the border fence. It issued a short video showing five youths approaching the fence. One of them pounds the fence with a club, while two others briefly cross through before jumping back to the other side.

Human Rights Watch said Israel has presented no evidence that rock-throwing or other violence seriously threatened the soldiers on the other side of the fence.

“The high number of deaths and injuries was the foreseeable consequence of granting soldiers leeway to use lethal force outside of life-threatening situations in violation of international norms, coupled with the longstanding culture of impunity within the Israeli army for serious abuses,” the group said.

Ismail Radwan, a senior Hamas official, said mass protests would continue as planned, despite Lieberman’s threats.

He said the Israeli defense minister’s latest comments should be seen as “more evidence of a war crime he (Lieberman) committed in Gaza last Friday.”

Lieberman has rejected international calls for an independent investigation.

On Tuesday, he warned Hamas against what he called “continued provocation.”

“We have established clear ground rules and we do not intend to change them,” Lieberman said during a visit to an Israeli communal farm near Gaza. “Anyone who approaches the border is putting his life in danger.”

Israel’s military spokesman, Brig. Gen. Ronen Manelis, has portrayed stone-throwing, tire burning and other actions by protesters near the border fence as “acts of terror.”

Briefing journalists Monday, he did not say in what circumstances protesters were killed Friday or why lethal force is justified if soldiers are not in apparent imminent danger. He argued that there would have been far more bloodshed in the event of a mass border breach.

In Gaza, protest organizers also prepared for the next confrontation.

Plans were circulated on social media to burn large numbers of tires on Friday, in hopes that thick black smoke would block the view of Israeli snipers. Others suggested trying to disrupt the vision of soldiers with mirrors.

In the town of Khan Younis in southern Gaza, teenagers collected old tires from repair shops, loading them onto three-wheelers. About 150 tires of all sizes were piled up at a traffic circle Tuesday, waiting to be transported to the nearby tent camp.

The planned protests seem to be the last hope for Hamas to try to break a border blockade imposed by Israel and Egypt in 2007, when the group seized Gaza from Western-backed Palestinian President Mahmoud Abbas. Two other blockade-busting strategies — war with Israel and reconciliation with Abbas — have failed.

Hamas has said the border protests would continue until May 15, the 70th anniversary of Israel’s creation. Palestinians mourn the date as the anniversary of their “nakba,” or “catastrophe,” when hundreds of thousands were uprooted from their communities in what is now Israel.

Two-thirds of Gaza’s 2 million people are descendants of refugees. Life in Gaza has become increasingly harsh after more than a decade of closures, with residents enduring daily power outages lasting hours.

Hamas has said the protests would culminate in a “March of Return,” implying the demonstrators would at some point try cross the border fence into Israeli territory.

However, Hamas officials have not specifically called for a mass breach of the fence.

(AP)