VATICAN CITY — Pope Francis and King Abdullah of Jordan agreed on Thursday that dialogue was the "only option" to end the conflict in Syria, the Vatican said, as the United States and its allies weighed plans for a military strike.

Abdullah flew to Rome specifically to meet the Pope to discuss the Middle East crisis. The king, Queen Rania, and the Pope spoke privately for 20 minutes in the Vatican's apostolic palace.

The king and the pontiff "reaffirmed that the path of dialogue and negotiations among all components of Syrian society, with the backing of the international community, is the only option to end the conflict and the violence that each day cause the loss of so many human lives, most of all among the defenseless population," the Vatican said in a statement.

Last Sunday, the Pope spoke of "atrocious acts" following an apparent poison gas attack that residents in a Damascus neighborhood say killed hundreds of people.

The Pope and the king met a day after U.S. officials described plans for multinational strikes on Syria that could last for days, and as Washington and its European and Middle East allies said Syrian President Bashar al-Assad must face retribution for using banned weapons against his people.