The United States says they will support Israel as they defend themselves from terrorists and Hamas.
Israel was celebrating a Jewish holiday on Saturday when Hamas crossed the Gaza Strip and began a ground invasion, as well as firing the first of thousands of rockets. Rockets have been fired across the border striking parts of southern and central Israel.
Israel's military have continued to fight back. Tanks and drones are guarding openings in the border fence to prevent more infiltrations. Several border communities have been evacuated.
Some 700 Israelis have lost their lives and some 130 more were kidnapped. There have been reports that some Americans were victims as well.
The declaration of war gives the green light for Israel to take "significant military steps" against Hamas.
Major U.S. airlines have suspended flights to Israel. American Airlines, United Airlines and Delta Air Lines suspended service as the U.S. State Department issued travel advisories for the region citing potential for terrorism and civil unrest.
American suspended service to Tel Aviv through Friday and issued a travel alert providing additional flexibility for customers whose travel plans are impacted.
The United States is standing with Israel and is sending military assistance. Warships and air support will be sent to the region close by.
Defense Secretary Lloyd Austin said he has ordered the USS Gerald R. Ford carrier strike group to sail to the Eastern Mediterranean to be ready to assist Israel. It is the most advanced aircraft carrier and has approximately 5,000 sailors and deck of warplanes will be accompanied by cruisers and destroyers.