Iran-aligned Iraqi armed group Kataib Hezbollah warned on Sunday it would resume attacks on U.S. troops in the region if the United States intervenes in the conflict between Israel and Iran.

The deadly conflict between Israel and Iran has entered a fourth day, with both sides firing waves of missiles overnight. Follow for live updates.

The conflict, the most intense fighting between the two countries in decades, has been met in the United States with feelings of “frustration and helplessness,” as well as heartbreak.

Israel and Iran have opened a new chapter in their long history of conflict. Israel launched a major attack with strikes early Friday that set off explosions in the Iranian capital of Tehran.

Israel decimated the group’s leadership last fall and degraded its military capabilities. Can the same strategy work against a far more powerful foe?

Israel unleashed airstrikes across Iran for a third day Sunday and threatened even greater force as some Iranian missiles evaded Israeli air defenses to strike buildings in the heart of the country. Planned talks on Iran’s nuclear program,