The airstrikes would be aimed at ISIS forces, weapons and critical supply lines between Iraq and Syria, a border that has effectively been erased as ISIS has advanced and seized territory this year.
The officials stressed that no decision had been made about airstrikes. They hinted that a decision could come by the end of the week.
President Barack Obama already authorized strikes against ISIS inside Iraq earlier this month. But U.S. officials have signaled over the past week, since the ISIS beheading of an American journalist seized in Syria, that stopping ISIS would require action in Syria, too.
The Syrian government said on Monday that it is ready to cooperate with countries fighting ISIS, including the United States, and would consider any strikes inside Syria an act of aggression unless Syria was consulted.
U.S. officials, who oppose the government of President Bashar Assad, said explicitly on Monday that they would not seek Assad’s approval for strikes inside Syria.