Sen. Elizabeth Warren (D-Mass.) speaks during a news conference in Kabul on July 4, 2017. (Rahmat Gul/AP)

Back from her first overseas trip to visit U.S. military personnel, Sen. Elizabeth Warren (D-Mass.) warned that the Trump administration is creating a “diplomatic vacuum” in Afghanistan by leaving key State Department posts unfilled at a time when a “whole-of-government strategy” is needed to end the 16-year-old conflict.

The Trump administration has been working for several months on a new plan for Afghanistan and Pakistan, but internal debates among the White House, the Pentagon and the State Department have delayed this even as militants continue to mount attacks in both countries. U.S. military leaders have asked to deploy 3,000 to 4,000 more troops to Afghanistan, a request that probably will be fulfilled by President Trump.

Warren traveled this week to Afghanistan, Pakistan and the United Arab Emirates as part of a bipartisan congressional delegation, making her overseas debut as a member of the Senate Armed Services Committee. Back in her Cambridge, Mass., living room on Thursday just 16 hours after returning home, Warren made clear: “I’m not there on a troop increase.”

“No one on the ground believes there is a military-only solution in Afghanistan. No one,” she said. “From the heads of state to the young man who walked us from one building to another in the embassy compound. No one — people at the forward operating base to anyone we stopped.”

“The Trump administration needs to define what winning in Afghanistan is and how we get to that,” the senator added. “They owe it to the deployed forces to provide the American people with a comprehensive, whole-of-government strategy that has not only a military angle, but also an economic and diplomatic plan.”

Trump has yet to nominate a U.S. ambassador to Afghanistan or neighboring Pakistan, two countries destabilized for years by terrorist groups that freely move across a porous border. Senior State Department positions entrusted with overseeing U.S. policy for Afghanistan and Pakistan remain vacant, and the acting director of the Office of the Special Representative for Afghanistan and Pakistan and her deputy stepped down last month as the administration is poised to close the stand-alone office, launched by veteran diplomat Richard C. Holbrooke.

Warren said she is perplexed by the administration’s decisions. “They’re not only talking about cutting up and down at the State Department, but also leaving major diplomatic posts unfilled. That’s dangerous,” she said.

One of several Democratic senators talked about as a potential 2020 presidential candidate, Warren has long been a target of Trump, who has been derided for nicknaming her “Pocahontas” — a reference to her claim of being part Native American, which was questioned during her 2012 Senate campaign.

The overseas trip marked the most visible demonstration of Warren’s work on defense matters — an area she is less known for after years of focusing on the nation’s economic recovery and financial regulatory reform.

Warren said she “committed to do my homework” when she joined the Senate Armed Services Committee, hiring policy experts for her staff and seeking out “extra reading and extra policy briefings from our government” and outside experts.

“But part of doing my homework is going and seeing it with my own eyes. There’s no amount of briefing that substitutes for standing on the ground and looking around. Nothing takes the place of talking to the people who are trying to execute on American foreign policy every single day,” she said.

Warren’s views on the situation in Afghanistan echo those of Sen. John McCain (R-Ariz.), chairman of the Armed Services Committee, who led the delegation, and Sen. Lindsey O. Graham (R-S.C.), McCain’s longtime friend and a fellow defense hawk. Speaking with reporters on July 4 before departing the country, McCain predicted that the conflict in Afghanistan would continue “on a low-burning simmer for a long time to come.” But he reiterated that only an aggressive U.S. effort to bolster Afghan military actions would force the Taliban to negotiate. “That won’t happen unless they feel they are losing,” he said.

Graham said he would tell Trump that “he needs to pull all our troops out” or build on the request for 3,000 to 4,000 more personnel.

Warren said she agreed with McCain and Graham that Trump and Secretary of State Rex Tillerson are creating “a diplomatic vacuum” in Afghanistan by not traveling to meet with top leaders and by leaving acting officials in charge of the U.S. Embassy and other diplomatic and economic projects.

“Look, the people who are there are doing their best, but they don’t have the perceived authority they need to get the job done,” she said.

The delegation also included Sens. David Perdue (R-Ga.) and Sheldon Whitehouse (D-R.I.).

In her conversations with U.S. military and diplomatic officials in Afghanistan, Warren said, she got no sense of how much longer it will take Defense Secretary Jim Mattis and top generals to deliver their plans to Trump or whether they are developing a more regional approach to account for the situation in Pakistan — as Tillerson has promised. In Pakistan, the senators were flown by helicopter to Wanna, in South Waziristan, to observe how the Pakistani army is clearing the border region of insurgents.

Warren called the Pakistani military’s work in that region “a real success story.” But she added that the Pakistanis “realize they’ve got a big border problem.”

“They’ve put a lot of effort into changing an area that was largely controlled by terrorists into an area that the government now controls,” she said, noting that the project is working because “they could fly in foreign visitors and they’re beginning to try to set up a local market, and civilians are beginning to come into the region.”