The U.S. and its allies strained to forge a response to Islamic State’s recent battlefield gains, touting efforts to supply Iraq’s military with more powerful weapons to fend off the militant group.

Top diplomats from more than 20 countries across the West and the Middle East met in Paris on Tuesday in a bid to refresh the coalition’s strategy for confronting the extremist group, which has in recent weeks seized the Syrian city of Palmyra and the Iraqi city of Ramadi, despite U.S.-led airstrikes.

The meeting, however, failed to yield any breakthroughs, highlighting the struggle U.S. allies face in driving back a group that has planted deep roots in the volatile region while also drawing fighters from around the globe. […]