World leaders are witnessing what one has called a "moment of profound crisis." They fear the conflict between Israel and the Islamist militant group Hamas, which is already unlike any in the Middle East in decades, will only escalate.

Israeli troops have seen Hamas fighters launch attacks that have killed more than 1400 people. They've retaliated with repeated airstrikes. Authorities in Gaza say at least 3,785 Palestinians have been killed.

Israeli units have been deployed along the border with Gaza, poised to cross over. On Thursday, Prime Minister Benjamin Netanyahu visited one staging ground to rally his troops.

Netanyahu said, "We are going to win with all our might. The entire nation of Israel stands behind you. We will deal a heavy blow to our enemies until we achieve victory."

Israeli Defense Minister Yoav Gallant said soldiers who are now looking at Gaza from a distance will see it "from the inside."

Israeli leaders had cut off supplies to Gazan civilians. However, after meeting with US President Joe Biden on Wednesday, Netanyahu says they will allow deliveries of food, water and medicine -- as long as they do not benefit Hamas. Aid workers expect 20 trucks could cross into Gaza as soon as Friday.

United Nations Secretary-General Antonio Guterres said they need to respond the "most basic needs" of civilians. He has called for an immediate humanitarian ceasefire.