KARACHI (AP) ― Pakistan’s president returned home early Monday, nearly two weeks after a surprise trip to Dubai for medical treatment sparked rumors that he might step down under pressure from the country’s powerful military.

President Asif Ali Zardari’s arrival will likely help quell speculation about his future. But officials have not spelled out exactly what was wrong with the president, and he is still under threat from a memo scandal that has upset the army and already forced the Pakistani ambassador to the U.S. to resign.

Zardari’s plane landed at an air base in the southern port city of Karachi shortly after midnight, said Manzoor Wassan, the home minister in Sindh province where Karachi is the capital.

The president flew to Dubai on Dec. 6 amid confusion over his medical state and reason for leaving. Officials released a statement by his doctor last week saying Zardari, who has a heart condition, had lost consciousness for several minutes and was suffering from pain in his arm. One associate has said privately that the president suffered a “mini-stroke” that had left no lasting affects.

Zardari is under pressure over his alleged connection to a secret memo sent to Washington in May seeking U.S. help in averting a supposed military coup, following the American raid that killed Osama bin Laden. Pakistan’s former ambassador to the U.S., Husain Haqqani, has been accused of masterminding the memo with Zardari’s support.

Both Haqqani and the president have denied the allegations, but the envoy resigned in the wake of the scandal. Pakistan’s Supreme Court is scheduled to begin a hearing into the memo scandal on Monday.

Pakistan has also been rattled by NATO airstrikes on Nov. 26 that killed 24 Pakistani soldiers at two army posts along the Afghan border.

More than 30,000 Islamists rallied against the U.S. in the eastern city of Lahore on Sunday, demanding Islamabad cut off ties with Washington. The protest highlighted the ability of hard-liners to bring their supporters into the streets, as well as lasting anger over the attack, which has complicated U.S. efforts to enlist Pakistan’s cooperation on the Afghan war.

The U.S. has expressed its condolences for the airstrikes, but this has done little to calm anger in Pakistan’s military, which has claimed the attack was deliberate. Pakistan has already retaliated by closing its Afghan border to supplies meant for NATO troops in Afghanistan and kicking the U.S. out of an air base used by American drones.

“All agreements (with the U.S.) should be terminated,” Hafiz Saeed, the head of the group that organized Sunday’s protest, Jamaat-ud-Dawa, told the crowd. “We say all agreements terminated the day the attack happened.”

Jamaat-ud-Dawa is widely considered to be the front group for Lashkar-e-Taiba, a militant organization that was started with help from the Pakistani government to fight archenemy India, but has been officially banned under international pressure.

Lashkar-e-Taiba is blamed for the 2008 attacks in Mumbai that killed 166 people. India has demanded Pakistan crack down on the group, but Islamabad has shown little willingness to go after Lashkar-e-Taiba or Jamaat-ud-Dawa.

Protesters at Sunday’s rally shouted, “A friend of the USA and India is a traitor.”

Pakistan’s alleged tolerance for Islamist militant groups has been one of the main sources of tension with the U.S. Washington has been especially frustrated with Islamabad’s refusal to target the Afghan Taliban and their allies and has even accused the country’s intelligence agency of supporting the groups.