Washington (CNN) Secretary of State Rex Tillerson visited Kabul on Monday in a brief, unannounced trip that had been shrouded in secrecy amid an uptick of violence in the Afghan capital.

Tillerson, who was on the ground for just over two hours, met with President Ashraf Ghani, according to the US Embassy and pool reports. The secretary of state then departed for Doha, Qatar.

The visit is part of Tillerson's week-long trip to the Middle East, South Asia and Europe and follows a deadly string of attacks in the war-torn country.

On Saturday, at least 15 people died in a suicide bombing in Kabul, which targeted army officers at a military academy about seven miles from the city center.

It followed suicide attacks on Friday that killed nearly 60 people at two mosques: a Shia mosque in Kabul and a Sunni mosque in the central province of Ghor.

There were no immediate claims of responsibility for Friday's attacks, but ISIS has claimed responsibility this year for other attacks on Shiite mosques.

The day before the mosque attacks, 43 Afghan troops were killed when Taliban militants stormed the Chashmawi military base in the Maiwand district of Kandahar province.

Strategy

President Donald Trump's Afghanistan strategy was first unveiled in August with the President vowing that the US would find victory in the 16-year war while no longer "nation-building."

Trump declared he would no longer announce troop levels but would focus on allowing US forces to target the Taliban and other terrorist groups wherever they were in Afghanistan.

The war, which has claimed more than 2,000 American lives, began less than a month after the September 11, 2001, terror attacks.

Over 8,000 US troops are currently deployed to Afghanistan. The majority of them -- about 6,900 -- are assigned to the NATO mission to train and advise Afghan security forces alongside approximately 6,000 troops from other NATO countries.

In August, Tillerson said the strategy was a "pathway for reconciliation and peace talks," and meant to pressure the Taliban to the negotiating table by making it clear there's no way to win on the battlefield.

In that plan, Trump authorized more troops and declared that the US would avoid nation building, concentrating instead on empowering the Afghans to fight their own battles. Under Trump, the US would also continue to engage regional neighbors, such as India and Pakistan, in efforts to stabilize Afghanistan.

The plan resembles the strategies of previous administrations, with a few tweaks and is deliberately short on details, including US troop numbers and how long the US will stay.

Taliban: US official preciously targeted

Security for Tillerson's visit was extra tight in the wake of a visit by the Defense Secretary James Mattis in September, which was marred by an aborted rocket attack on Hamid Karzai International Airport in Kabul.

The Taliban claimed responsibility for the attack and claimed it was deliberately targeting Mattis.

The rockets, which caused no damage or injuries, were fired at the facility hours after Mattis and NATO Secretary General Jens Stoltenberg had already departed.

Tillerson: Time Iran-backed militias left Iraq

Before flying to Doha, Tillerson visited Saudi Arabia, where he sent a message to Iranian-backed militia and foreign fighters in Iraq, where the US is supporting the government in its fight against ISIS.

"Any foreign fighters in Iraq need to go home and allow the Iraqi people to regain control of areas that had been overtaken by ISIS and Daesh that have now been liberated," Tillerson said, speaking in Riyadh alongside Saudi Foreign Minister Adel al-Jubeir.

"Allow the Iraqi people to rebuild their lives with the help of their neighbors," he said.

Last week, US-backed forces declared the liberation of Raqqa, Syria, more than three years after the city emerged as ISIS's de facto capital.

Following Saudi Arabia, Qatar and Afghanistan, Tillerson's trip will also include stops in India, Switzerland and Pakistan, where he will meet with senior leadersto discuss South Asia strategy and economic ties between Washington and Islamabad.

In August, when releasing his strategy for Afghanistan and South Asia, Trump called out Pakistan for its role in harboring for terror groups.

"We have been paying Pakistan billions and billions of dollars, at the same time, they are housing the very terrorists we are fighting ... that must change immediately," Trump said at the time