北约在威尔士举行峰会

World leaders are gathering Thursday in Wales for the start of a two-day NATO summit expected to focus on the conflict in Ukraine and the threat of Islamic extremists in Syria and Iraq.

In the Welsh city of Newport, NATO is expected to debate formation of a rapid response military force capable of deploying on short notice to trouble spots in eastern Europe.

Ukraine's President Petro Poroshenko is due to attend as a non-member invitee, and officials say he will meet with Western leaders on the sidelines of the gathering.

Russia, which has strongly opposed any NATO presence near its borders, has denounced the idea of a rapid response unit.  Earlier this week, Russia said it will review its own military strategies in eastern Europe if NATO endorses creation of the force.

Also at the summit, NATO leaders are expected to discuss strategies for countering the threat from the Islamic State militant group that has overrun large parts of northern Iraq and eastern Syria.

The U.S. has been carrying out airstrikes against the group in Iraq, while other alliance members have begun providing humanitarian aid.