Afghanistan’s new president, Ashraf Ghani, has managed to be more productive in one day than his predecessor, Hamid Karzai, was for months. After nearly a year of stalling by Karzai’s administration over concerns about excessive civilian casualties, Afghanistan and the United States finally ratified a Bilateral Security Agreement on Tuesday — a document that took Afghan and American negotiators a year to draft and one that was the subject of so much confusion and frustration for the Obama Administration this year.

Rather than signing the agreement, Karzai had pledged to leave the task to his successor. So when Ghani and his challenger, Abdullah Abdullah, formed a unity government after a disputed presidential election this summer, the new administration in Kabul signed the security document on its first official day of business.

A lengthy accord riddled with diplomatic language, the agreement allows the United States to keep close to 10,000 troops in Afghanistan for the explicit purpose of advising and training the Afghan military and pursuing what remains of Al Qaeda’s leadership in the country. The Americans will have access to nine bases spread across Afghanistan in order to ensure that advising and training activities are as widely distributed as possible. The United States will have an obligation “to seek funds on a yearly basis to support the training, equipping, advising and sustaining of” the Afghan army and national police and American troops will have full immunity from prosecution in Afghan courts. If Afghan authorities detain an American for whatever reason, the Afghan government must hand that soldier over to his own government.

For the Obama Administration, the ratification is both a political achievement and an assurance to its critics that America will finish what it started thirteen years ago. With Iraq’s security in absolute chaos only three years after Western armies pulled out, the security agreement with Afghanistan will provide the United States with the tools and resources that are needed to prevent a similar cataclysmic outcome from occurring there.

Although long-term arrangements have now been made for American forces, it will ultimately be up to the Afghan army and police to continue taking charge of their own security. Far from being in a frontline combat role, American personnel who remain in Afghanistan after this year will serve as a force multiplier — not a force replacement — for the Afghan troops. The new government of Ashraf Ghani will be severely tested by the Taliban insurgency which continues to chip away at central government control in the east and south and remains altogether a formidable force in the remote provinces along the border with Pakistan.

Given the frenetic pace of casualties the Afghan army has endured over the past year, the new government in Kabul will need all the help it can get from the United States and NATO allies to hold the Taliban at bay and prevent the insurgency from encroaching on the country’s major cities. The Bilateral Security Agreement is the blueprint for how that assistance will be given.