Iran launched scores of ballistic missiles into Israeli territory on Tuesday in what it described as an expression of its “legitimate right to self-defense under the UN Charter.” The attack came hours after Israel announced a ground incursion into Lebanon, and as UN experts warned of the dire consequences of regional hostilities.

In a statement, Iran’s Islamic Revolutionary Guard Corps (IRGC) — the country’s armed forces — said the attacks aimed to avenge the deaths of Hamas leader Ismail Haniyeh, Hezbollah leader Sayyed Hassan Nasrallah, and Iranian General Abbas Nilforoushan in Israel’s ongoing conflicts in Gaza and Lebanon.

The IGRC then warned of the possibility of further escalation, again citing international law In doing so:

Warning is given that if [Israel] responds militarily to this operation, which is in accordance with the country’s legal rights and international laws, it will face subsequent crushing and destructive attacks.

Responding to the attacks, Israeli Prime Minister Benjamin Netanyahu urged Israeli citizens to obey the directives of local military authorities, and to remain united through the attack.

Reliable casualty figures are yet to be reported.

The attack came shortly after Israel announced it would expand its military operations in Lebanon to include a ground invasion. A statement by the Israel Defense Forces described the move as “limited, localized, and targeted.”

The latest escalation follows widespread calls for a ceasefire between Israel and Hezbollah. Earlier Tuesday, UN High Commissioner for Human Rights Liz Throssell had warned of the devastating consequences a ground invasion could have, saying:

Israeli strikes in Lebanon have reportedly killed over 1,000 people in the past two weeks alone. Hundreds of thousands have also been displaced in Lebanon, alongside those recently fleeing into Syria, and over 60,000 have been displaced in Israel since Hezbollah’s escalation of missile fire from October 8 last year.

Israel has faced growing international calls to respect international humanitarian law in recent months, amid reports of devastating civilian death tolls in Gaza, where it has been engaged in a ground war with terror organization Hamas for nearly a year, and, more recently, Lebanon.  It faces ongoing charges of genocide against the people of Palestine before the International Court of Justice.

Leaders from across North America, Europe, East Asia, and the Middle East called for a 21-day ceasefire and compliance with UN Security Council resolutions aimed at brokering an end to regional hostilities in Lebanon and Gaza.