The U.S. is sending more American troops to Israel, said the Pentagon’s press secretary, Maj. Gen. Pat Ryder, on Monday. The move is a response to concerns that a massive Israeli air strike campaign could herald the outbreak of a regional war.

Israel began the large-scale series of air strikes in the country of Lebanon on Monday morning, targeting assets of the Lebanese militant group Hezbollah. The Israeli military announced online that it had carried out attacks on over 300 targets in the country, making it one of the largest offensives since the current hostilities broke out in October of last year, when Hezbollah fired rockets and conventional artillery into Israel in support of the Palestinian terrorist group Hamas in Gaza.

The Lebanese health ministry announced that the Israeli strikes have killed 274 people and wounded over 1,000 so far. The attacks, which are concentrated on the southern region of Lebanon bordering Israel, have induced thousands of Lebanese civilians to flee the area for the safer northern portion of the country. Some reported receiving automated phone calls urging them to evacuate the region.

The offensive sharply increases tensions between the two countries, which have already reached dangerous levels. Last week, Israel blew up thousands of pagers and other devices carried by Hezbollah operatives, killing nine, injuring nearly 3,000 people and inflicting a harsh blow to the group’s communications network.

The conflict threatens to reignite the Israel–Lebanon war, which, despite being ended in 2006 by a UN-brokered ceasefire, has continued to smolder.