The U.S. and its allies are ratcheting up efforts to prevent the war between Israel and Hamas from engulfing the wider region, acting on concerns that an invasion of the Gaza Strip by Israeli forces could prompt Iran to enter the conflict.

The U.S. has warned Iran in recent days through back-channel talks about the risks of escalation, White House national security adviser Jake Sullivan said Sunday on CBS News’ "Face the Nation." He said the U.S. couldn’t rule out Iran intervening either directly or via Hezbollah, the Lebanon-based militia group that it sponsors.

Israel’s emergency government has vowed to wipe out Hamas and mobilized 300,000 reservists ahead of a major ground attack. With hostilities centering around the blockaded enclave in Israel’s south, the U.S. has asked Qatar to tell Hezbollah not to open up a second front to the war, a person familiar with the negotiations said, asking not to be named because the talks are delicate.