BEIRUT, Lebanon — After a bizarre three-week international sojourn during which he shocked his country by suddenly quitting the government, Saad Hariri, the prime minister of Lebanon, is back home and still in his job — at least for the time being.

But while his return and the promise of political dialogue about the country’s future have temporarily pulled Lebanon back from the brink of a political void, the issues that set off the crisis remain as serious and intractable as they were before he left.

This small country remains a battleground in the struggle between Saudi Arabia and Iran for influence in the Middle East. It is also home to Hezbollah, the militant group that has grown into a regional force in its own right.

Although Mr. Hariri has denied it, Lebanese politicians and foreign diplomats say that Saudi Arabia forced him to resign — and even considered replacing him with his brother — in the hope of inciting a change in the status quo that would weaken Hezbollah.