Two days after Trump ceded unilateral authority on Afghan troop deployments to the Department of Defense, the Pentagon wasted on time and according to AP, the Pentagon will send 4,000 additional American forces to Afghanistan to support existing forces and in hopes of breaking a stalemate in a war that has now been passed on to a third U.S. President. The deployment will be the largest of American manpower under Donald Trump’s young presidency.

According to AP, the decision by Defense Secretary Jim Mattis could be announced as early as next week, and was prompted by "the rising threat posed by Islamic State extremists, evidenced in a rash of deadly attacks in the capital city of Kabul, has only fueled calls for a stronger U.S. presence, as have several recent American combat deaths." Asked for comment, a Pentagon spokesman, Navy Capt. Jeff Davis, said, “No decisions have been made.”

Trump’s decision Tuesday to give Mattis authority to set force levels in Afghanistan mirrored similar powers he handed over earlier this year for U.S. fights in Iraq and Syria. The change was made public hours after Sen. John McCain, the Senate Armed Services Committee’s Republican chairman, blasted Mattis for the administration’s failure to present an overarching strategy for Afghanistan. McCain said the U.S. is “not winning” in Afghanistan, and Mattis agreed. The finality of the decision isn’t entirely clear. While Trump has handed over the troop level decision-making, there is nothing preventing him from taking it back. Mattis has repeatedly stressed that increasing the number of U.S. troops in Afghanistan would take place within a broader, long-term strategy for stabilizing Afghanistan. In congressional testimony this week, he said the strategy will take into account regional influences, such as Pakistan’s role as a Taliban sanctuary. Regional powers Iran, India and China, which all have political stakes in the fate of Afghanistan, also must be considered.

The bulk of the additional troops will train and advise Afghan forces, according to the administration official, who wasn’t authorized to discuss details of the decision publicly and spoke on condition of anonymity. A smaller number would be assigned to counterterror operations against the Taliban and IS, the official said.

From the Afghan side, reactions were split: Daulat Waziri, spokesman for Afghanistan’s defense ministry was reluctant to comment on specifics Friday but said the Afghan government supports the U.S. decision to send more troops. “The United States knows we are in the fight against terrorism, ” he said. “We want to finish this war in Afghanistan with the help of the NATO alliance.”

However, another Afghan lawmaker, Nasrullah Sadeqizada, however, was skeptical about additional troops and cautioned that the troop surge should be coordinated with the Afghan government and should not be done unilaterally by the United States. “The security situation continues to deteriorate in Afghanistan and the foreign troops who are here are not making it better,” he said.

The gamble to send even more troops in Afghanistan is a big one for the president who inherited America’s longest conflict with no clear endpoint or a defined strategy for American success, though U.S. troop levels are far lower than they were under Presidents Barack Obama and George W. Bush. In 2009, Obama authorized a surge of 30,000 troops into Afghanistan, bringing the total there to more than 100,000, before drawing down over the rest of his presidency.

Trump, who barely spoke about Afghanistan as a candidate or president, concentrating instead on crushing the Islamic State group in Syria and Iraq, may be underestimating the potential risk he faces by sending more troops in harms way. His predecessors both had hoped to win the war. Bush scored a quick success, helping allied militant groups oust the Taliban shortly after the Sept. 11, 2001, attacks, before seeing the gains slip away as America’s focus shifted to the Iraq war. In refocusing attention on Afghanistan, Obama eliminated much of the country’s al-Qaida network and authorized the mission that killed Osama bin Laden, but failed to snuff out the Taliban’s rebellion.

Obama set a cap a year ago of 8,400 troops in Afghanistan after slowing the pace of what he hoped would be a U.S. withdrawal. Nevertheless, there are at least another 2,000 U.S. troops in Afghanistan not included in the official count. These include forces that are technically considered temporary even if they’ve been in the war zone for months.

That said, Mattis’ deployment of more troops will be far smaller than Obama’s. While the new troops could raise fears of mission creep, Mattis told lawmakers this week he didn’t envision returning to the force levels of 2010-11, when Obama thought he could pressure the Taliban into peace talks. Despite heavy losses, the Taliban fought on and in recent months appear to be gaining traction.

Meanwhile, this is the kind of news that awaits Trump: there have been almost 2,400 U.S. military deaths in Afghanistan since 2001. Three U.S. soldiers were killed and another was wounded in eastern Afghanistan this weekend in an attack claimed by the Taliban.