Al-Qaida, behind the Sept. 11, 2001 terrorist attacks on America and scores of other massacres worldwide, is beginning to look like an unorganized gang of amateurs – in comparison to the so-called Islamic State.

Formerly known as the Islamic State in Iraq and the Levant, IS seems to have more militant followers and more resources than al-Qaida. It certainly controls more territory.

Wherever IS terrorist troops go, the Sunni Muslim group slaughters those who do not adhere to their severe religious beliefs. That includes Shiite Muslims, Christians, Jews and others.

Already, the IS controls part of Syria and much of Iraq.

This week the IS expanded its zone of aggression to Lebanon. It claimed responsibility for a suicide bombing in Beirut. That is a clear demonstration the IS has militant supporters in that country, possibly poised for more attacks.

For some time it appeared the IS was just another splinter terrorist group, similar to others inspired by al-Qaida.

Now we know better. The IS is a major threat to the entire Middle East – to hundreds of millions of people and resources including vast deposits of petroleum. Continuing IS attacks could spark a region-wide war.

What, if anything, do U.S. officials have in mind to curb the IS? Even in Iraq, President Barack Obama’s administration has adopted an arms-length attitude toward fighting the terrorists. What will happen if they step up their assaults in Lebanon or move into other countries?

We know now al-Qaida’s success might have been prevented by U.S. action. Will we adopt the same attitude toward the IS?