NEWPORT, Wales — America’s top diplomatic and defense leaders pressed a core coalition of 10 nations to summon the willpower to go after the Islamic State group in Iraq militarily and financially, and said they must build a plan by the time the UN General Assembly meets in about two weeks.

In a private meeting with the foreign and defense ministers from the United Kingdom, France, Australia and six other nations, Secretary of State John Kerry said leaders need a clear strategy and a solid idea about what each country will contribute to the fight. And, while noting that many won’t be willing to engage in military strikes, he said they can instead provide intelligence, equipment, ammunition or weapons.

In remarks at the beginning of the meeting, Kerry called for a “holistic approach,” attacking IS operatives “in ways that prevent them from taking over territory, that bolster the Iraqi security forces, [and] others in the region who are prepared to take them on, without committing troops of our own, obviously. I think that’s a redline for everybody here, no boots on the ground.”

Kerry and Defense Secretary Chuck Hagel identified five “lines of effort” to combat the extremist jihadist group — “military support to our Iraqi partners; stopping the flow of foreign fighters; countering ISIL’s [as the group is sometimes called, using a former acronym for the Islamic State in the Levant] financing and funding; addressing humanitarian crises; and de-legitimizing ISIL’s ideology.”

“We have the technology, we have the know-how,” Kerry said. “What we need is obviously the willpower to make sure that we are steady and stay at this.”

Hagel, sitting alongside Kerry, said the group of 10 nations represents a core coalition that will be needed to face the insurgent challenge. He said the group can then be expanded.

The secretary of state also noted that a new inclusive Iraqi government would be conduive to international efforts to combat the Islamic State.

The US proposed to enter an “immediate conversation with a new Iraqi government”  about the “potential for additional training and equipping of the Iraqi Security Forces at the federal, regional, and provincial level.”

The morning meeting was a late addition to the NATO summit here, and is part of a broader US strategy to bring more nations into the fight against the Islamic State militants who have taken control of large swaths of northern and western Iraq and across the border into Syria.

The session, which also included dignitaries from Germany, Canada, Turkey, Italy, Poland and Denmark, focused on the Islamic State group in Iraq, but Kerry said there are obviously “implications about Syria in this” and suggested they could discuss that later in the day.

“We very much hope that people will be as declarative as some of our friends around the table have been in order to be clear about what they’re willing to commit, because we must be able to have a plan together by the time we come to (the United Nations General Assembly),” said Kerry. “We need to have this coalesce.”

Their statements came several days after a video released by the terror group Tuesday showed the brutal execution of an American journalist, the second in as many weeks. The grisly beheading prompted horrified reactions from the international community.

Steven Sotloff next to his IS captor in a video released Tuesday, September 2, 2014. (Screen capture: SITE/Twitter)

Steven Sotloff next to his IS captor in a video released Tuesday, September 2, 2014. (Screen capture: SITE/Twitter)

Steven Sotloff, who has since been revealed to have been Jewish and held Israeli citizenship, disappeared in Syria last August and was shown to have been beheaded in the online video by an IS jihadist with a London accent. The jihadist is believed to be the same executioner who appeared in a video last month killing US journalist James Foley.