ISIS

The Obama administration's diplomatic point man in the international fight against the Islamic State group says the extremists have been losing control over territory and that "this perverse caliphate is shrinking."

Fewer Americans are traveling to fight alongside the Islamic State and the power of the extremist group's brand has diminished in the United States, FBI Director James Comey said Wednesday.

A former office-supply store supervisor who pleaded guilty to conspiracy for helping his brother travel to the Middle East to join the Islamic State group was sentenced Tuesday to 15 years in prison by a judge who denied his attorney's request for a lighter sentence.

Vice President Joe Biden, visiting Iraq on Thursday, described progress toward defeating the Islamic State group as "serious" and "committed" despite a crippling political crisis that threatens those gains.

Some of the four Minnesota men facing trial next month for conspiring to join the Islamic State group had discussed the possibility of attacks in the United States, according to a document filed by prosecutors.

The Obama administration is making the case that Iran is drawing down its elite fighting force from Syria in an effort to allay fears that Tehran is using its powerful Islamic Revolutionary Guard Corps in Syria to strengthen its influence across the Middle East. Yet the Iranian government said Monday it has dispatched commandos to the war and it is still taking high-ranking casualties.

Dozens of world leaders assembling Friday for a nuclear security summit will confront a disparate array of modern-day threats, ranging from government actors like North Korea to murkier groups like the Islamic State.

Investigators say they are still looking for at least one suspect in the attacks seven days ago, when suicide bombers killed 32 people at Brussels' airport and in a subway station near the European Union headquarters. Three suicide bombers also blew themselves up.

The Pentagon said Friday it was moving to increase the number of American troops in Iraq amid new strikes this week that killed the Islamic State's finance minister and other senior leaders. Still, top U.S. defense officials say the deaths won't "break the back" of the extremist group, which is in a fierce fight for an ancient city in Syria and claimed responsibility for bombing a soccer stadium in Iraq.

Syrian government forces were on the verge Thursday of recapturing Palmyra, an ancient town in central Syria controlled by the Islamic State group, having pushed closer to its outer edges with the support of Russian airstrikes.