Joint Chiefs Chairman Gen. Joseph Dunford said Wednesday that the Syrian Kurdish YPG militia, backed by the U.S. in the effort to rout ISIS from Raqqa, has an office in Moscow.

"I'm going to be quite honest with you," Dunford told senators questioning the scope of the accelerated campaign to defeat ISIS, the shifting loyalties of the various factions supported by the U.S. in the fight, and the potential threat from Russia's backing of opposing groups.

"The group that we are supporting, certainly at the political level, has been engaged in Russia," he said of the YPG, or People's Protection Units. "The YPG has a political office in Moscow itself, but the groups that we're providing support to on the ground are not being supported directly by Russian military forces."

Turkey considers the YPG an extension of the PKK (Kurdish Workers Party), which has been labeled a terrorist organization by Turkey and the U.S. Turkey has repeatedly threatened to attack the YPG, but the U.S. considers the group the most effective rebel fighting force in northeastern Syria.

Army Lt. Gen. Stephen Townsend, commander of Combined Joint Task Force-Operation Inherent Resolve, has said that the YPG fighters will take part in the eventual assault to take Raqqa, the self-proclaimed capital of the Islamic State of Iraq and Syria.

Dunford was testifying with Defense Secretary Jim Mattis before the Senate Defense Appropriations Subcommittee on a $30 billion supplemental for defense spending this year, but the hearing turned into a wide-ranging overview of how the money would be used.

Mattis disclosed that the 30-day plan he gave President Donald Trump late last month to speed up the anti-ISIS campaign was short on specifics. "We've got the skeleton plan put together. We're fleshing it out," he said, adding it will be weeks or months before it is a finished product.

Mattis described the strategy as an "interagency-developed report" that embraces "economic, diplomatic, military, covert means."

"We should have this done in the next couple of months, if that long," he said. "It may not even take us another month, but we're still putting it together."

In the meantime, a small contingent of Army Rangers and Stryker combat vehicles have moved into Manbij, about 70 miles north of Raqqa, to provide a "visible presence" of U.S. forces to ward off any attempts by Turkish-backed local forces or Syrian army troops backed by Russia to enter the city.

In addition, about 400 Marines from the 11th Marine Expeditionary Unit have entered Syria to set up a firebase with M777 .155mm howitzers to support an assault on Raqqa. The 2nd Brigade Combat Team of the 82nd Airborne Division is also deploying to Kuwait for potential use in the train, advise and assist role in either Iraq or Syria.

When his detailed plan for defeating ISIS is complete, Mattis said, the U.S. will seek to put pressure on the group on several fronts simultaneously. The plan is to "increase the number of fights in a number of locations so they have cascading problems. We intend to throw them on their back foot."

The Iraqi Security Forces, advised by the U.S., have used similar tactics in the months-long campaign to retake Mosul in northwestern Iraq. The attack had stalled until the ISF began pushing against ISIS on three separate avenues of approach.

Mattis suggested that a major increase in the number of U.S. troops on the ground may not be necessary to carry out the new plan. Currently, "a few troops have been added for fire support or for monitoring," he said in a reference to the Army Rangers in Manbij and the Marines at the firebase near Raqqa.

"They're not there permanently," although they are in addition to the 500 U.S. troops currently authorized for Syria, he said.

In seeking to walk the senators through the complicated battlefield in Syria, Dunford drew a distinction between the YPG and the affiliated group called the "Afrin Kurds" who operate well west of Manbij in the Afrin area of northwest Syria and are directly supported by the Russians.

"I can confirm for you that the specific group [Afrin Kurds] that's being supported by the Russians is not a group that has received training, equipment, resources from us in the northwest part of Syria," Dunford said.

"In the specific groups that we do provide support to and the ones that we have asked to provide additional support to, we do have a very detailed vetting process that we use to mitigate the risk of weapons or equipment falling in the wrong hands," he said.

On the budget, Mattis called on Congress to "look reality in the eye" and approve a $30 billion supplemental in defense spending for fiscal 2017. "Looming threats have outstripped the level of resources we have been allocating to defense," he said.

The additional funding request, backed by President Donald Trump, "will help address the worsening security situation confronting us around the globe," Mattis said.

"We must recognize that hesitation now to invest in defense would deepen the strategic mismatch between our future security and the military means to protect our people and freedoms," he said.

Mattis also urged lawmakers not to neglect the role of diplomacy in avoiding conflicts. Trump has proposed major cuts in the State Department's budget, but Mattis said "diplomatic solutions will remain our preferred options."

However, "we cannot deny the role of our military in setting the conditions for diplomatic progress."

Mattis said the $30 billion would "get our aircraft back in the air, our ships back to sea, and our troops back in the field with refurbished or new equipment and proper training. This is a necessary investment to ensure our military is ready to fight today."

The $30 billion includes $24.9 billion in the base budget and $5.1 billion for Overseas Contingency Operations -- the so-called "war budget" to fund the anti-ISIS campaign.

At a Pentagon briefing last week, budget officials said the $30 billion would pay for 28,000 more soldiers and modernization of Army aircraft, drones and air defense systems; 6,000 more service members for the Navy and Marine Corps, as well as pilot training and 24 F/A-18 Super Hornet fighter jets; and 4,000 airmen, as well as more pilots, additional F-35 Joint Strike Fighters and C-130 Hercules tanker variants, and upgrades to F-15 and F-16 fighter jets.

-- Richard Sisk can be reached at Richard.Sisk@Military.com.